Training and Competing With a Continuous Glucose Monitor

So, while it appears that eating a doughnut is the cause of the glucose spike and the two are correlated, you’re missing an important factor that needs to be taken into account for true causation. It generally is highly useful and very interesting when you see different correlations, but it’s also important to do the testing yourself so that you can discover what works for you and what doesn’t.

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reading hundreds of scientific studies, I believe that maintaining a lower and more stable blood glucose level is one of the most important things I can do for my cardiovascular health. Using a CGM has made a profound difference in my average daily and nightly blood glucose levels, has held me accountable to the choices I make in my diet, and I believe it has been a significant contributor to improving my longevity and vitality.

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If your glucose is constantly dropping and you’re not ingesting more carbohydrates, there will be only so long that you can exercise. Your muscles contain enough glycogen for 60 to 120 minutes of intense exercise, and your liver contains between 30 minutes of stored glycogen for a total combined possible amount of 2.5 hours of stored glycogen. For optimal performance in events longer than two hours, you’ll want to eat carbohydrates before these glycogen supplies are depleted. By eating the correct type of carbohydrates at the right time, you can carefully regulate your glucose to maintain an optimal level before, during, and after your workouts and/or competitions. Ensuring you’re fueling correctly before your events allows you to start your competitions ready to compete from the time the gun goes off. Recognizing during your exercise the different scenarios that your glucose levels might undergo, will keep you informed so that you can decide whether you need to ingest a quick acting carbohydrate or a

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What you eat after your workout is just as important, especially if you’re planning on working out the next day. Your CGM will help you track your recovery. It will give you insights on optimal foods to consume after the workout or before bedtime in order to improve recovery.

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When your blood glucose levels drop, you begin to feel lethargic, sleepy, and you might even find yourself in a bad mood. And, of course, you won’t be as productive as when your glucose is higher versus when it’s close to your baseline, and stable. When you’re on a roller coaster of high glucose then low glucose, it’s hard to perform well throughout your workout, and it’s tough on your liver, pancreas, and even your brain as you try to focus and concentrate. High blood glucose is not as big of a problem if you’re staying below 200 mg/dL, which is around the top limit for normal healthy athletes that don’t have type 1 or 2 diabetes. However, high glucose is not something you’re striving for. More is not better in this case, as high blood glucose levels can cause inflammation, damage to the internal walls of your arteries and vessels, and puts a large strain on your pancreas to secrete more and more insulin to stabilize your body back to its basal level.2 A stable glucose, and it doesn’t have to be perfect, will allow you to perform at a high level, be focused throughout your workout and/or competition, and will ultimately help you to focus on what’s important, whether that’s the next point in your tennis game, the next hill on your bicycle, or the next set of weights at the gym.

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Like any measuring tool, whether that is a heart rate monitor, stopwatch, or step counter, once you become aware of something and you can measure that thing, you’ll improve it. Take that measuring tool away and you lose the ability to know what exactly is happening and, in this case, what is happening inside your body and how it reacts to ingested foods. I know that when I am using my CGM, I still make different food choices even after having used one now for over two years. I know that eating tortilla chips will absolutely blow up my blood glucose to over 200 mg/dL every time I have some, but if I don’t have a CGM on, I’ll reach for that bag of chips! Even athletes that I coach have said to me, “Woohoo, I am off sensor! I’ll have that big pastry please,” when we have stopped during a training ride out cycling. The accountability factor of using a CGM is a real thing, and it can keep you on track.

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The great news is that all the training you currently do also improves your metabolic health, including making you more sensitive to insulin, reducing the risks of disease, type 2 diabetes, and nonalcoholic fatty liver disease. At the same time, training also helps to improve your numbers in the five indicators of good metabolic health (mentioned at the start of this paragraph). So, it’s an upward spiral of improvement. Exercise more, improve your metabolism and metabolic health, wear a CGM, understand how your glucose level responds, and make better choices to further improve your glucose stability and therefore metabolic health.

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Type 2 diabetes, or adult-onset diabetes, occurs when your cells become resistant to insulin. Cells need insulin to “open the door” for glucose to go into the cell, but in type 2 diabetes, these cells no longer respond to insulin and therefore leave the glucose molecules to circulate in the bloodstream. A type 2 diabetic could have a glucose value as high as 400 mg/dL, whereas anything over 140 mg/dL is considered inflammatory to the body and causes damage to the epithelial (inner) layer of the vessels and arteries. This damage is then fixed by plaque and eventually the plaque becomes thick and hardened, and finally so clogged that blood flow is stopped, which results in a stroke or heart attack. Let’s prevent that! And yes, even athletes can have clogged arteries. There are countless stories of well-known and little-known lifelong endurance athletes that have had heart attacks because of clogged arteries. Diet also plays a huge role as well, and you can’t out-exercise a bad diet. Repeat after me: “You can’t out-exercise a bad diet.”

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When you create more stability and less variability in your average daily glucose, you’ll undoubtedly improve your insulin sensitivity. Couple this with a healthy diet that is high in fiber and low in saturated fats, and you’ll be well on your way toward reducing your risk of acquiring type 2 diabetes.

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These are accumulated averages over that time period. With the truly continuous glucose monitors, you’ll learn how your recent food intake and exercise impacted your glucose, giving you an opportunity to adjust insulin dosing (if you are type 1 or 2) and see the impact of your meals or snacks in almost real time. Using a CGM is a truly revolutionary way to measure glucose levels and has been well proven to compare with highly calibrated venous sampling in nondiabetic individuals.9 Since CGM devices measure interstitial glucose rather than actual blood glucose concentrations, a 5 to 10 minute lag exists between actual blood glucose and reported CGM glucose readings.10 This is important to remember when you’re competing, and we’ll talk more about this in later chapters.

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Hypoglycemia occurs when blood glucose levels fall below normal and is usually considered below 70 mg/dL. It is often referred to as “low blood sugar,” and can result from prolonged fasting, intense exercise, or certain medical conditions. Symptoms of hypoglycemia can include shakiness, sweating, rapid heartbeat, and, in severe cases, confusion, seizures, or coma. As an athlete, a sudden drop in blood glucose during prolonged exercise is known as “bonking” or “hitting the wall,” which severely impairs performance. So read that sentence again. A sudden drop is the key descriptor. Dr. Stephen McGregor, professor of exercise physiology at Eastern Michigan University said, “You don’t have a bonk just because you drop below 70 mg/dL. You can bonk if you’re used to a high level of blood glucose and then that drops a certain amount. You could be competing with a glucose from 140 to 180 mg/dL for hours and hours, and then you drop to 120 mg/dL. You could experience all the symptoms of hypoglycemia, and your performance will be severely impacted. A big part of your performance is your body’s perception and the level of glucose you are accustomed to. When you’re accustomed to being hyperglycemic, then when that level drops dramatically, you experience the bonk.”

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Hyperglycemia, the opposite of hypoglycemia (low blood glucose), refers to having elevated blood glucose levels. This is generally thought to be over 126 mg/dL during fasting and over 180 mg/dL two hours after your meal. The glucose level for hyperglycemia hasn’t been determined yet for nondiabetic athletes during exercise, as using CGMs for non-diabetics is so new. I have found in over two years of researching across 12 different sports that athletes can compete at a high level with their glucose at 200 mg/dL or greater. So in non-diabetics, during exercise, hyperglycemia might be considered over 200 mg/dL, but this is only an observation at this point. More research is needed.

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Trained athletes have roughly a total of two and a half hours of stored glycogen in their muscles and liver. In the muscles, there can be as much as two hours of stored glycogen (300 g) in highly trained athletes and 30 minutes of stored glycogen (100 g) in the liver, so elite athletes could have up to around two and a half hours of stored glycogen. For recreational athletes, this could be only one and a half hours of stored glycogen, so there could be a vast difference between recreational and elite professionals.14

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Glycogenesis Glycogenesis is the process by which glucose is converted into glycogen for storage in the liver and muscles. This process happens when there is an excess of glucose in the bloodstream, such as after a meal. What this means is that this process is taking the glucose out of the bloodstream and reducing your glucose number on your CGM. Glycogenesis is also crucial for maintaining blood glucose levels within a normal range and for ensuring that the body has sufficient energy reserves for future use.

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Gluconeogenesis What happens when you deplete all your glycogen stores, and you don’t ingest more glucose? That’s when your body’s back-up system kicks in. This is called gluconeogenesis and is the process of producing glucose from non-carbohydrate sources, such as proteins (amino acids), lactate, and fats (glycerol). This process primarily occurs in the liver and is essential during prolonged fasting, starvation, or intense exercise when glycogen stores are depleted. Gluconeogenesis helps maintain blood glucose levels and provides energy to organs that rely heavily on glucose, such as the brain. Your body will protect your brain at all costs from starving from lack of glucose. It goes so far as to shut down the rest of your body to preserve your brain. You won’t be able to walk and will collapse from fatigue, a direct result of your body protecting your brain and ensuring it has glucose to survive.

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And here’s the information you’ve been waiting for, and why this all matters: without sufficient glucose, cells wouldn’t be able to produce the necessary ATP to function effectively, leading to a decline in overall athletic performance. Our muscles, brain, and liver are particularly dependent on blood glucose. How does this impact more specifically the muscles, brain, and liver? When we exercise, train and/or compete, our muscles require a tremendous amount of energy. Most of the energy used by the muscles is in the form of stored glycogen, but those stores must be in the muscles to be used. However, if needed, glucose can be rapidly taken up by muscle cells and converted into ATP through glycolysis. This process provides the immediate energy needed for muscle contraction.

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Finally, the liver acts as a glucose storage unit, or gas tank so to speak, storing glucose in the form of glycogen. When blood glucose levels drop, the liver releases glucose back into the bloodstream through a process called glycogenolysis. The liver also plays a role in gluconeogenesis, which is the production of glucose from non-carbohydrate sources (proteins and fats), which ensures a steady supply of glucose during fasting or prolonged exercise. So yes, you can exercise just on proteins and fats, but this must be at a low level of intensity. In the book Sport Nutrition, Dr. Asker Jeukendrup and Dr. Michael Gleeson wrote, “The main problem with the use of fat as a fuel for exercise is the rate at which it can be taken up by muscle and oxidized to provide energy. Fat oxidation can only supply ATP at a rate sufficient to maintain exercise at an intensity of about 60% of O2max.”

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As soon as you put some glucose in your mouth, insulin begins secreting and stops the fat burning process (lipolysis). Once glucose enters the bloodstream from the digestive system, insulin acts like a key, unlocking cells so they can absorb glucose. And if you just read about the process of the Krebs cycle in the Powering the Body section above, you’ll know that the glucose can then be converted into ATP or stored as glycogen for later use, particularly in the liver and muscles. It’s also very important to understand that your body also secretes insulin when you eat proteins and fats. This is important to understand the implications regarding a high protein/high fat diet as many believe that by reducing the glucose spikes by abstaining from carbs, they’re avoiding any future issues with regards to type 2 diabetes. This is flawed thinking and will be detailed in Chapter

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you eat too much food, or more than you expend, insulin also promotes the storage of excess glucose as fat in adipose tissue (fat). It’s worth repeating that insulin inhibits the breakdown of fat and glycogen, helping to maintain energy balance in the body. What does this mean to you as an athlete? If you’re trying to reduce your fat percentage by cutting out calories and fasting, then keep in mind that as soon as you put carbs in your mouth, that fat burning process is stopped. If you don’t produce insulin like a type 1 diabetic (who has to inject insulin), glucose would remain in the bloodstream, causing hyperglycemia (high blood glucose), which has been proven to cause a range of health issues, including damage to blood vessels, nerves, and organs. That damage then leads to cardiovascular damage, a possible heart attack, and even death. So, insulin is very important, along with a well-functioning pancreas!

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Without insulin, the body’s ability to regulate blood glucose levels is severely compromised, leading to hyperglycemia. If left untreated, this condition can result in serious health complications, including diabetic ketoacidosis (DKA), a life-threatening condition where the body begins to break down fat for energy, producing high levels of ketones and leading to acidic blood. People with type 1 diabetes, a condition where the pancreas produces little to no insulin, require external insulin administration to manage their blood glucose levels. Without insulin treatment, individuals with type 1 diabetes would not survive. Even in type 2…

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Besides the immediate risks of hyperglycemia, a lack of insulin would also mean that cells could not efficiently absorb glucose, leading to severe energy deficits. The brain, which relies almost exclusively on glucose for energy, would be particularly affected, resulting in cognitive impairment, confusion, and, in extreme cases, coma. This is what happens when someone enters a diabetic coma. Without insulin, the body’s ability to store energy in the form of glycogen and fat would be severely impaired, leading to rapid weight loss, muscle wasting, and malnutrition. In the long term, chronic hyperglycemia without…

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Insulin resistance occurs when the body’s cells become less responsive to insulin, meaning more and more insulin is required to achieve the same effect. As a result, the pancreas compensates by producing more insulin, leading to elevated insulin levels (hyperinsulinemia). Over time, this can exhaust the pancreas and lead to conditions such as type 2 diabetes. Insulin resistance is what you’re trying to prevent in athletic events and in your everyday life. Reducing high sugar intake, ultra-processed foods, saturated fats, sedentary periods, and keeping your weight down, will help reduce insulin resistance.

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During exercise, insulin levels naturally decrease to allow for the mobilization of glucose and fatty acids from storage sites. This process is essential for maintaining blood glucose levels and providing a steady energy supply to working muscles. After exercise, insulin sensitivity temporarily increases, meaning cells are highly responsive to insulin’s effects. This heightened sensitivity allows for post-workout shakes and meals to be quickly metabolized and the glucose to be taken up in the muscles and liver quicker, enhancing your post-workout recovery. Therefore, you want a glucose spike after your workout. That recovery shake, containing carbs and some protein, that you ingested is important because it causes as much insulin to release as possible, so you can optimize this recovery process aiding in muscle repair and growth.18

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Movement Exercise is your biggest tool to reduce your circulating blood glucose. When your glucose is high, go for a brisk walk, ride your bike, do some work in the gym, play racquetball, or anything else to get you moving. The carbohydrates you ingest will be turned into glucose and start circulating in the bloodstream. Your body prioritizes using those carbohydrates as fuel first before requiring the breakdown of glycogen from the liver into glucose (glycogenolysis). This is great for endurance athletes, as it helps to preserve your liver and muscle glycogen during the first two-thirds of a competition and saves those precious glycogen stores for the last third of competitions. If you don’t use this circulating…

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For your purposes, you need to always remember that if you start exercising, your glucose level will most likely drop, especially if it’s just an easy- to moderate-intensity workout. If it’s a low-intensity workout, you’ll burn mostly fat. However, a very low-intensity workout, like a walk after dinner, will cause your glucose to drop since your body will prioritize this readily available source of energy. This drop in glucose is normal, so don’t be surprised when you see it occur. In most cases, your glucose will drop but then come back up to normal level as your body finds an equilibrium between the supply of blood glucose and the demand from the muscles. If your glucose value is already on the low side of your normal level, then exercise will drop it even more and your liver will begin releasing glycogen into the bloodstream to take up the slack. If your glucose level is on the high side after a heavy carbohydrate meal, then exercising will…

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This one should be obvious. What you eat has a massive influence on your glucose levels. If you eat only protein, then your glucose level will barely budge. If you eat only fats, your glucose levels will barely budge. You need glucose in your system to be able to measure it. When you ingest sugars, whether a simple sugar like fructose or a complex sugar like starch, they’re going to raise your glucose. How much you ingest of each type will determine the height of the peak of your glucose, and your metabolic efficiency will determine how quickly it drops or stays up. It’s not always that cut and dried though, as the height and length of the peak is also determined by the fiber content, protein amount, and fat amount in your food. This combines to determine your glucose level. To make it even more complicated, what you had in your previous meal and your current training status can also impact your glucose response. Overall, though, what you put in your mouth has a large influence on your glucose levels. As we saw in Figure 1.4, a high-carbohydrate meal can send your blood glucose through the roof. In Figure 1.5, we have an athlete that has a normal glucose level while sleeping, down around 90 mg/dL. He then gets up and has a high-carbohydrate breakfast, which spikes his glucose to nearly 180 mg/dL, before it begins to dissipate. At lunch time, he goes out for a meal at a Mexican restaurant. He indulges in some chips; a large burrito filled with beans, rice, and veggies; and finishes it off with four small chocolates back at the office. This sends his glucose value to 200 mg/dL, possibly higher, and keeps it there for over four hours! Clearly, this athlete didn’t need this much fuel on board.

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Mood Excitement, nervousness, anticipation, anxiousness, stress, and fear are moods/feelings that can raise your blood glucose. These feelings (and others) can release adrenalin (epinephrine), which causes the stimulation of glycogen breakdown in the liver and fat burning in the fatty (adipose) tissue (lipolysis). Anytime you trigger the sense of “fight or flight,” adrenalin is released, and glucose is released into the bloodstream to deal with the threat. Your body doesn’t know if it’s about to be chased by a bear or if you’re just getting ready for a big presentation at work! Technically, this is a reaction in the sympathetic nervous system, which prepares the body for this fight or flight, whereas the parasympathetic nervous system restores the body to a calm and relaxed state. So yes, if your glucose shoots up right before a big presentation at work, it’s not an error. It’s a real release of glucose so that you have the energy you need to “wow” the boss. That also can happen in a heated argument, when you’re excited for an upcoming event, are nervous before a big competition, or feel stressed by a tough situation. Your mood absolutely influences your glucose levels. So, if you’re watching your numbers and you see them go up and wonder why, think back to your mood and see if that was the cause.

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WHAT DOES THIS ALL MEAN TO YOU? This is complicated stuff. Just like how I don’t know how my cell phone works—what all the transistors, chips, signals, etc. are—I know when I pick up the phone, I can call someone around the world instantly. You don’t need to know every single detail about the biochemistry behind your glucose value being measured on your CGM. What’s important to know while reading this book and observing your glucose levels on your CGM, is that your glucose response is based on many factors. There is no absolute, where Y always equals mx+b, in glucose monitoring.

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Mood, movement, and nutrition are the big factors. Within nutrition, there is timing, type of food, state of fasting, fat-burning state, and more. If you’ve just eaten a large meal that was 60% carbs, 30% protein, and 10% fat, followed by a brisk hour-long walk, you might see a drop in your glucose because you were using all those circulating sugars you ingested at dinner. How about being in a 16-hour fasted state and then eating three donuts for breakfast? You might get a spike in glucose that goes over 200 mg/dL vs. if you eat those same three donuts at the end of a normal day where you’re eating every three hours or so.

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Movement impacts your glucose levels dramatically, whether you’re going for an easy walk after dinner or doing VO2 max hill repeats on the local trail. The spike that comes from intense exercise can turn into a slow downward drop as you use your glycogen stores and circulating glucose, which makes it so important to understand when you need to ingest more food to stay ahead of the drop. An easy walk after your dinner is something that I highly encourage, as very low-intensity exercise helps to reduce the circulating glucose that you just ingested from dinner and helps to keep your nightly average glucose lower.

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IT’S DIFFICULT TO BE CERTAIN about the impact of different foods on your performance. The responses to foods can be wildly different from one person to another. One person might have oatmeal with strawberries, flax, a tablespoon of almond butter, and almond milk for their breakfast and barely get glucose rising from 80 milligrams per deciliter (mg/dL) to 90 mg/dL, and they might not be able to get a spike throughout the whole day. Another person might have the same small meal and get a fast spike that sends them from 80 mg/dL to 150 mg/dL. The same meal and proportions but vastly different responses. The cause of this is multifactorial and hard to blame on any one component. It could be related to your meal the night before, the intensity of your training the day before, how depleted (or not) your glycogen stores are, the quality of your sleep, individual physiological factors, the level of stress you’re exposed to, and even your age. It could also be related to the drugs you’re taking. Keep in mind that other chronic medical conditions and/or the therapy you’re taking might interfere with your glucose levels/trends.

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Simple carbohydrates (or simple sugars) consist of basic sugar molecules (short chain). They’re quickly digested and absorbed by the body. When you think of simple carbs, think quick energy and rapid increases in blood glucose. Some examples of these are fruits (fructose) and dairy products (lactose). Simple carbs are also commonly added to foods, such as table sugar, corn syrup, and high-fructose corn syrup. What are common foods that have simple carbs? Soda, baked treats like cookies and pies, packaged cookies, fruit juice concentrate like orange juice, and breakfast cereals. Simple carbs are hidden in many foods as well, including salad dressings, sandwich bread, and yogurt.

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What about high-glycemic and low-glycemic foods? When we talk about simple and complex carbs, it’s also important to clearly understand the Glycemic Index (GI) and how that relates to your blood glucose. Are all simple carbs high glycemic? Are all complex carbs low glycemic? The GI is a metric that ranks your carbohydrate intake based on post-meal glucose responses in comparison to the “gold” standard of pure glucose, which scores 100 on the GI. Foods that are higher on the index contain more sugars and, therefore, produce a higher blood glucose level. Foods that are lower on the GI have less sugars and consequently cause a lower glucose level or possibly no rise at all.20 Therefore, the GI is a way to rank foods containing carbs on a scale from 1 to 100 based on how much they affect your blood sugar levels. Two foods with the same amount of carbohydrates can have different GI numbers, so just because you eat a gel with 100 kilocalories (k/cals), doesn’t mean it will give you the same glucose response as eating a sports bar with 100 k/cals.

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Foods are grouped into three categories based on their GI: low, medium, and high. A score of 100 means that a food has a big effect on your glucose levels (and insulin), while a score of one indicates little effect. GI can help you make better sports-nutrition choices based on what you need at the time. Maybe you’re about to start a bike race and you want to “prime” your body for the start, so you want to eat something that’ll give you a quick spike just 10 minutes before you begin. In this case, you would choose a high-glycemic food, which usually means more processed, simple carbs and less or no fiber. On the other hand, you could be at hour five of a full-distance triathlon and know that you’ve five more hours to go, so a lower-glycemic food would be more appropriate to give you a slower release for longer-term energy. Here’s the GI ranking:

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The reason some foods make glucose shoot up fast, is that simple carbohydrates in them, such as refined sugars and white flour, are easier for your body to change into glucose (the sugar your body uses for energy) as these are short-chain sugars and quickly broken down. In contrast, carbs such as those in vegetables and whole grains are digested more slowly, as mentioned earlier, as complex carbs with fiber and more long-chain molecules take longer for the body to break down. If you eat lower-glycemic foods, it will be easier to regulate your blood glucose and keep your energy levels more stable for a longer period. If you eat a lot of high-GI carbs, you may have a harder time controlling your blood sugar and could quickly put yourself on a “roller coaster” glucose response, which we’ll talk about in later chapters.

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You need glucose, and in the right amount, to enhance your athletic performance, whether that’s during training or a competition. Making sure that you take in just the right type of carbs at the right time will make the difference between feeling energized and ready to go at the start, or lethargic and ready for a nap. Your body makes hormones to control glucose levels. These hormones include insulin and glucagon. “Insulin potentially coordinates with glucagon to modulate blood glucose levels; insulin acts via an anabolic pathway, while glucagon performs catabolic functions.”22 Insulin moves glucose from your blood into your other organs. Glucagon releases glucose stored in your liver when you need more blood sugar. Your body should normally keep glucose levels at a healthy level. I’ll elaborate more on insulin throughout this book and by the end of the book, you’ll have a clear understanding of how insulin works and its role in performance.

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Examples of low-GI foods include: – Green vegetables and raw carrots. – Legumes like lentils, black beans, kidney beans, soybeans, pinto beans, etc. – Nuts like almonds, walnuts, cashews, peanuts, etc. – Unsweetened plant milks, non-fat unsweetened yogurt, and milk. – Fruits like blackberries, blueberries, grapes, oranges, apples, pears, etc. Examples of medium-GI foods include: – Vegetables like corn and beets. – Fruits like figs, bananas, pineapple, and cherries. – Most dried fruits like raisins, apples, figs, and cranberries. – Unsweetened whole cereals and most cereals containing whole oats. – Long grain rice, brown rice, pasta, barley, rice noodles, and couscous. – Honey and real maple syrup. – Many breads containing multigrain and nuts, whole-grain wheat, and rye, as well as some sourdough breads. Examples of high-GI foods include: – Pure table sugar. – Risotto, white rice, sticky rice and rice cakes. – Bagels, white bread and most crackers. – Cooked carrots and baked or boiled potatoes. – Doughnuts, candies and chocolates. – Fruits like watermelon, and all fruits in canned syrup. – Sweetened…

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Can You Change the Glycemic Index of Foods? The GI is just a measure of the single piece of food in either a raw or cooked state. You can change the GI of many foods based on how you cook the food, store the food, and how you combine it with the other foods on your plate. It can also depend on how ripe that food is. For example, a green banana has a GI of around 30, and a “just beyond” ripe banana has a GI of around 60. The green banana contains more resistant starch and less sugar. FIGURE 2.1 Glycemic Index of Different Potatoes Baked russet potato 111 Instant mashed potato 87…

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Cooking and food prep. If you add in fat, other fibers, proteins, and acid (such as lemon juice or vinegar), then you’ll lower the GI. By combining a high-glycemic food with other low-glycemic foods, you can easily reduce the glucose spike and peak. For example, eating a salad with vegetables and a simple olive oil and vinegar dressing first, followed by white rice with tofu will help to significantly reduce the blood glucose spike and peak, versus eating the white rice all by itself. Cooking time also impacts the GI and if you cook a lower-glycemic food, like yams, so long that it breaks down the fiber, it will no longer be a lower-glycemic carb. Even pasta, a meal that…

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Storing your food. Surprising, but true: if you put starchy foods with a higher GI in the refrigerator overnight, straight after cooking them, they’ll undergo a chemical reaction causing the starch to become more “resistant.” When you eat foods with resistant starch, you can’t digest them as easily, which lowers the GI and, in turn, reduces your glucose spike. Resistant starches are one of the latest ways that many bread…

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Ripe fruits and veggies. The GI of many fruits, such as figs, pears, raspberries, and blackberries, goes up as they ripen. Unripe fruit or vegetables take longer for your body to digest because they contain more fiber and fewer naturally developed sugars. A ripened fruit or vegetable has had more time to create sugars, by turning fiber into sugar, so it digests more quickly and your glucose will increase faster and peak higher. With this all in mind, what about fats and proteins? These have a GI of 0, as they contain no carbohydrates, so they don’t affect blood glucose levels. It’s important to understand that this doesn’t mean you should add in tons of fats and proteins to better reduce your blood glucose spikes, because not having a spike is not always the answer. You want the appropriate change in blood glucose for the appropriate training or competition. Repeat after me: “The keto diet is not the answer. The keto diet is not the answer. The keto diet is not the answer.” As mentioned in the previous chapter, when you first start using a continuous glucose monitor (CGM), you’ll immediately see what foods begin impacting your blood glucose and many of you will freak out and think that you need to stop eating all carbs. This is not the answer if…

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When you eat carbs, proteins, and fats (along with how you eat them and the order in which you eat them) this has an incredible impact on your blood glucose levels and correspondingly your performance. Let’s start with the easiest examples and work toward the most complicated. Our first example is that of a bodybuilder that has a high-carbohydrate, medium-glycemic meal about 30 to 40 minutes before an intense session in the weight room. There is very little protein and fat in his meal (less than 15%). It’s a truly high-carb meal of day-old pasta with a touch of olive oil, 12 celery sticks dipped in hummus, two slices of Ezekiel bread with almond butter, and a raw apple. In Figure 2.2, notice how his blood glucose rises within 15 minutes of his meal and peaks about 30 minutes after his meal, at about the same time he started his gym session. (Reminder: the time-to-response is individual and with this kind of meal it will be around 30 minutes to max spike, but it may still vary from athlete to athlete.) Starting from a 90 mg/dL start point and peaking at 140–150 mg/dL at the start of the session, will allow him to start the weight workout with more energy and hopefully accomplish his goals for that session. This is an example of what you want to do before your workout; you want to raise the glucose levels. As you can see in Figure 2.2, as he…

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The next example shows how a reactive hypoglycemic crash before a workout can negatively affect the workout. A reactive hypoglycemic crash happens after you ingest carbs—generally simple but can be complex—that cause insulin secretion to rise. If this happens too far in advance of the workout, your body sugar will have already dropped down when your workout starts. Once the workout starts, you’ll reduce the glucose levels even more. This combined effect of a higher insulin release with exercise causes the reactive hypoglycemic…

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This runner has a relatively lower baseline and generally stays around 80 mg/dL throughout the day (see Figure 2.3). He had a meal of a sandwich with chips and a sugary soft drink at noon, which took his glucose level from 80 to 120 mg/dL and then dropped it down to 65 mg/dL about an hour later. This is an example of a reactive hypoglycemic crash. This occurs when the athlete ingests carbs too quickly. The pancreas releases insulin pulling the glucose out of the bloodstream, but since the insulin secretion is high, it results in dropping glucose levels below the baseline. The pancreas really has no idea how much insulin to release, well, not no idea, but it’s not exactly certain after each meal! Moreover, it doesn’t know that you need to start the workout. Therefore, after the meal and before the workout, this runner felt like he was low in blood glucose (known as “bonking” by endurance athletes), low in energy, and needed something to help bring up the glucose levels before his…

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these two relatively uncomplicated examples, we see how timing and the volume of food intake can really make a difference between a good workout and a poor one. Now let’s look at a more complicated one where Bobby Julich, a former professional cyclist who won the silver medal in the 2004 Olympics and placed third in the 1998 Tour De France, raced in a local gravel bicycle race as a Masters Athlete in the 50+ category. In Figure 2.4, we see the graph of Bobby’s race. The dashed grey line is the wattage he produced, the dotted green line is his heart rate, and the solid green and black line is his glucose level. Bobby primed his system with 40 grams of carbs about 10 minutes before the race started, so he would start the race at 120mg/dL and be ready for the hard effort right at the start of the race, as these gravel races start intensely. Once he was in the front group of racers, adrenalin released and caused his body to release even more glucose from its stores of glycogen, causing his glucose to go over 200mg/dL for over 40 minutes. As the glucose lowers over the next 30 minutes, Bobby takes a gel of 30 grams of carbs to boost his glucose back up. But this was a bit too much, and his body released more insulin than needed, and he experienced a mild hyporeactive glycemic crash just before 11:00 a.m. Since Bobby felt low in energy, he took in more gels, and his glucose shot up to almost 200mg/dL again, but this time the race becomes more intense and he has to respond to multiple “attacks” by the competition. He used this glucose that he just ingested in pushing harder to beat his competition, causing it to go back down again. Around 11:45 a.m., the pace eased off and his glucose swung back up, this time because the intensity of the race had lowered but also because his body was still releasing a maximum amount of glucose from the stores of glycogen in the muscles. In the last 30 minutes, his glucose dropped significantly and he needed to have another gel in order to prevent from being hypoglycemic in the final minutes of the race. As you can see, it’s quite difficult for someone to time their glucose intake with the unknown intensity of a gravel bicycle race, even for someone that has had a very successful and long career as a professional. FIGURE 2.4 Cyclist’s Blood Glucose During a Race Description 11 Former professional cyclist Bobby Julich races in a local masters 50+ gravel

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Our next example is a pure and spicy roller coaster for a day! See Figure 2.5. This athlete started out with a big glucose spike for breakfast at 8:00 a.m., which came down at the start of the ride, and he spent the rest of the day experiencing blood glucose highs and lows. This is what you’re trying to prevent! This is stressful for the body but will also give you very inconsistent feelings and energy levels throughout the ride. You’ll experience high energy as the glucose increases but lower energy, and bonking, as it drops. Think of it as a struggle for the body: it continuously tries to bring your glucose to baseline or “homeostasis.” Homeostasis is the condition in which your body maintains for optimal function. This is the toughest scenario to manage during a ride and especially during a race. We’ll see another example of this in Chapter 6. After each drop in glucose, the athlete ate more carbs causing a peak of glucose. His pancreas overreacted releasing too much insulin, driving the glucose levels down and causing the athlete to eat another high-carb, high-glycemic food to raise his glucose and energy levels. This culminated in a peak after five hours of riding, as the group he was riding with decided to race the final hour home. He drank a Red Bull and ate a candy bar just before this section and hoped that it would be enough to get him to the finish without a serious hypoglycemic crash. Once you’re on the “roller coaster,” it’s not only tough to get off, but you have to accept your fate and just keep pounding carbs to the finish and hope you’ve enough in your pockets to make it to the finish line. In this case, he did make it, but just barely, as you can see by the big crash at 4:00 p.m. Fortunately, it was an easy 15-minute journey home followed by a recovery shake and meal. After the activity, observe how his glucose levels stabilize and maintain equilibrium. This is a great example of what to prevent in a race or hard training ride. In this case, the athlete started off with a poor breakfast selection and then ate simple, high-glycemic carbs the entire day, instead of choosing lower-glycemic, complex carbs with some proteins and fats, which could have made a big difference.

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Four different athletes, with different timings, foods, and training, results in four different outcomes. There is no “one-size-fits-all” in blood glucose. To determine the optimal timing for your training and competition, you’ll have to do some experimentation to learn what works for your body. There are some important guidelines that you should consider in timing your ingestion of carbs: 1. Prime the system: For an intense workout or competition, you should “prime” the system, by intaking glucose 10 to 15 minutes before the beginning of your effort. This works best if you’re going to be “full gas” from the start of the workout or competition, and shortcuts the time it would normally take for your body to respond and dump glucose from the liver into the bloodstream. This can give you an advantage right from the start. 2. Maintain the levels: During a workout, it’s important to maintain your glucose levels by regularly intaking glucose and proteins, so that you don’t just “spike” your glucose. If you’re using simple sugars in a drink or food, you’ll need to include some sort of protein and/or fat to mute a blood glucose spike and keep the levels relatively even. It’s important that you make sure to test which product (type and quantity) works the best in your case (in terms of glucose time-to-response and the max peak) before you lock in the training and/or competition protocol. Another tip that helps is to sip slowly but often, rather than taking a gel in one go. This can create a more stable response. One athlete I have coached loves the little gummy chews as their preferred sports nutrition, as they can perfectly titrate the dosage. They put two of the chews/blocks in their mouth, suck on them for five minutes and then chew them up. They watch their glucose levels and if they stay the same after five more minutes, they’ll repeat with two more chews/blocks and continue this way until they start moving the trending arrow upward. This is a much better way to maintain your level instead of stuffing eight of them in your mouth at once, and creating a big spike and possible hypo crash. 3. Sometimes you need a spike! There are many times during your training and/or competition that you’ll need sugar and need it now! This generally happens when you’re low and on the verge of hypoglycemia (bonking). 4. Eating too early can be bad: Traditionally, athletes have been told to eat three hours before their event. While having a solid meal three hours before the event or training allows you to digest the foods more completely, if you don’t supplement with other foods within the hour before your effort, you could have low glucose levels at the start. It’s fine to eat three hours before your event or training (giving your body the time to get back to homeostasis). Just know that the hour before, you’ll want to make sure you watch your CGM and see how your glucose is doing so you can ingest more food if needed. 5. Avoid the roller coaster! It’s important to…

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Sequencing of Food Intake How does the order of the food that you intake impact your glucose levels? Does this matter during training or competition, or in life for that matter? Can you make a profound change in your body’s response just

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What I mean by food sequencing is that the order in which you ingest your food matters. Most of us sit down at the table with a plate of food and move from one food to the other, eating whichever food next that takes our fancy. We never think about the order of carbs, proteins, and fats on our plate, and many times the foods we eat have all three ingredients in them. However, by “stacking” your food correctly, you can reduce the blood glucose rise and maintain a longer and more moderate amount of blood glucose. This is a simple yet revolutionary way to eat your meals, which does take a little discipline but no extra energy.

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Start with your salad first, eat it completely. Heck, you might do this anyway! Maybe this is why salad is always served first at restaurants. When you eat salad, use only olive oil and vinegar as the dressing. This avoids the nasty sugars that are used in most commercial dressings, and avoids seed oils, which are not great for you (more on that in Chapter 8). The vinegar in the dressing contains acetic acid. While it’s not entirely clear what mechanism causes your glucose to lower after ingesting vinegar, there are some scientific theories. The acetic acid in vinegar increases the rate at which glucose uptake occurs in the muscles, most likely from an improvement in insulin action in skeletal muscle. Vinegar also has been proven to enhance glycogen repletion in animal studies.23 This combination can reduce the glucose rise that you might see without including vinegar first. It’s also thought that vinegar can reduce gastric emptying. In a study, admittedly small, of 10 healthy, regular weight people, scientists observed that indeed, vinegar reduced both blood glucose levels and insulin concentrations after a high-starch meal. They wrote: “The mechanism is probably a delayed gastric emptying rate.”24 Another interesting study done on rats using balsamic vinegar found that it improves the function of beta cells in the pancreas, and those beta cells are the ones that…

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With the food stacking method in mind, now let’s stack your veggies on top of the salad. Eat all of your vegetables next. Don’t have a bite of carbs or protein while eating your vegetables, eat all your vegetables completely. By adding in additional fiber, any carbohydrates coming later will be even more slowly absorbed. After your vegetables, eat all your protein. Again, eat all the protein, whether that is tofu or steak, eat it all now. Finally, eat your carbs. (Isn’t it interesting that tradition is that we always have our sweets or dessert last!) This is the top of the food stack and will be digested later and more slowly as your body has to work through the fiber and proteins first, with the carbs coming in more slowly. The impact this has on your blood glucose is profound! Try eating the same dinner two days in a row and looking at your CGM data to see the differences. When you food stack, the spike will be much,…

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Food stacking is good for training and competition purposes, as it is for life. By making a simple yet revolutionary change to the order of how you eat foods, you can improve your energy for your workouts and your events. In your daily life, this will also reduce your average daily blood glucose, the peaks of your spikes, and the stress on your…

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BLOOD GLUCOSE HACKS There are numerous ways that you can reduce your blood glucose spike, both the peak of it and the duration of the rise. Why would you want to do this though? For those that might already be in the prediabetic range using the hemoglobin A1C (HbA1c) measure from 5.7 to 6.4, it’s important to significantly reduce your blood glucose spikes and improve your insulin sensitivity. Yes, it’s reversible and by changing lifestyle and habits around food and exercise, you can do a lot to improve your HbA1c. If you’re below 5.7, in the normal range, then it’s also important to reduce your spikes, because you don’t want to become prediabetic in the future and want to maintain a more stable level of blood glucose. Constantly raising your blood glucose up and down on the “roller coaster,” affects your energy level, mood, and ability to maintain focus.

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Let’s also consider your daily average blood glucose number. Even if you’ve a very normal and healthy glucose/insulin response to high-glycemic foods, constantly spiking your glucose levels to 180–200 mg/dL and over will absolutely raise your daily average blood glucose and HbA1c. For example, if you’re cruising along at 90 mg/dL, then have a meal that is predominately high glycemic and your blood glucose rises to 180 mg/dL within 30 minutes, and then drops back down to 90 mg/dL at 75 minutes after your meal, your average blood glucose might be 135 mg/dL for that entire 75 minutes. Conversely, if you ensure that you eat a low-glycemic meal and your blood glucose rises to 120 mg/dL and back down to 90 mg/dL again, your average might be 100 mg/dL over the 75 minutes. Raising your blood glucose to a high level, even if you’ve very normal and good insulin sensitivity, will increase your daily average glucose. This might not matter for an occasional meal but if you do this every day for a lifetime, it could cause you to become a type 2 diabetic later in life (alongside other risk factors).

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Conversely, I want to encourage you to not obsess about keeping your glucose low all the time. Repeat after me: “Keto (and the carnivore diet) is not the answer. Keto is not the answer. Keto is not the answer.” Many of you’ll start with your CGM and see all those blood glucose spikes as you eat your normal diet that you’ve been eating all your life. Then you’ll experiment with just eating protein and fats, and find that those spikes go away. Yes, they go away because you’re not ingesting any carbohydrates, so of course your blood glucose is not going to rise. However, by increasing your protein (animal and vegan) and your fats, especially saturated fat, you’re very likely to be causing long-term trouble (more on this later). As an athlete working to improve, presumably you’ll be doing some high intensity exercise, and these require carbohydrates! To do those efforts over 80% of your threshold heart rate, you’ll need carbs and stored glycogen in the muscles and liver. Yes, there are athletes out there that run on pure protein and fats, but they’re limited to very low-intensity…

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Hacks to Reduce Glucose Spikes Apple cider vinegar. This is a well-known hack that you can ingest 30 minutes before you eat a high-carbohydrate meal. Most studies have all focused around using two tablespoons (10 mL) of apple cider vinegar (ACV) mixed with three to four ounces of water 30 minutes before your meal. This absolutely works, as mentioned earlier in this chapter under the section “Sequencing of Food Intake.” There are many studies to back up this phenomenon and I encourage you to dig deeper into the referenced studies earlier in this chapter. Lemon/lime juice. Squeeze some lemon/lime slices into your water at mealtimes. These also contain citric acid and will work similarly to how the acetic acid in ACV works to help reduce your spikes. This is another great reason to drink water with your meals. Ketone esters. Ketone esters (KEs) like what is made by the industry standard company, deltaG®, can reduce your blood glucose spikes and your steady-state blood glucose too. One study found that by ingesting a KE drink 30 minutes before an oral glucose tolerance test, reduced circulating glucose by 11% in adults with obesity, 15% in young, healthy participants and improved glycemic response by 17%. “A reduction in steady-state glucose by 10% was observed by both nonobese and obese adults. The mechanisms underlying the glucose-lowering effects of KE are not entirely clear. The small, yet immediate, increase in insulin secretion after KE ingestion may be sufficient to inhibit hepatic glucose production.”27 Alcohol. While I do not recommend this to help mute your blood glucose spikes and reduce the circulating blood glucose in your bloodstream, it does work. When the impact of alcohol was studied on healthy, lean individuals, it was found that a relatively small amount of alcohol (about one and a half drinks) consumed an hour before a high-carb meal can reduce post-meal glucose levels and even lower insulin levels, as compared to eating the same meal without alcohol.28 It’s a range that depends on the person, as some reduced their glucose by 16% whereas others reduced it by 37%. So why is this happening? First off, alcohol inhibits the production of new glucose in the liver through the gluconeogenesis process, which can lead to lower circulating blood glucose levels. Secondly, light to moderate alcohol consumption can potentially result in a short-term…

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What is your optimal glucose level for performance? How does it change at different intensities? What about right before your workout or competition? Where should you maintain your glucose level during your event? What are important metrics to watch out for during your workout?

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STEP 1: GATHER DATA When you first apply your continuous glucose monitor (CGM), your goal is to gather data and observe your individual trends. You might want to change your diet every time you see your glucose levels spike, but you need to resist this temptation. Gather at least two weeks of data on your normal diet. Whatever you’re eating now is your normal diet. After you’ve established that norm, then you can start making changes as you go along. With your new CGM, you’ll want to track all meals and snacks, exercise, and sleep to make sure you capture all glucose metrics for these. You’ll do this is by creating an “event” (different apps call it different things, but we’ll call them events for the purpose of this book). When tracking your meals, you should create a new event when you start eating a meal, and end the event after there has been a blood glucose spike and it comes back down to your equilibrium point or normal average blood glucose. This way the event captures before the meal, the response of the blood glucose after the meal and when it comes back down at the end of the meal to your norm. This is important. See Figure 3.0.

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You’ll do the same for your sleep, when you wake up in the morning. Open your CGM app and mark the time you went to sleep, which is usually characterized by a sudden drop in blood glucose (unless of course you ate a big bowl of ice cream and chocolate sauce before bed, then it will continue to go up during your sleep!) and encompass your full sleep period to when you wake in the morning and get out of bed. FIGURE 3.0 Sample Event from Your CGM Description 15 Be sure to create a range around your entire glucose spike to ensure you have the correct average glucose value for it. Note: If you shower in the morning, then you’ll see a “fake” spike (also called an “artifact” of the sensor) because of the sharp temperature swing of the water. This is not a real change in your blood glucose, but a result of the temperature sensor inside the CGM measuring incorrectly because of the sudden change in temperature. This can also occur if you go into a sauna or

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STEP 2: LEARN YOUR BASELINE The first thing you should do when you get your CGM applied is to learn your average daily glucose levels and observe what is getting you out of that 70–140 milligrams per deciliter (mg/dL) zone. This is done simply by wearing the CGM and observing what your “normal,” or basal, levels are when your body is in glucose homeostasis. Your body wants to maintain your glucose levels in a narrow window, so it’s constantly striving to get back to that stable level. You find yours by looking at the average glucose after you’ve eaten, and then allowing the glucose levels to rise and come back down and stabilize. For example, let’s say that your glucose is trucking along at a pre-meal baseline of 85 mg/dL. You eat a nice healthy meal of vegetables and fruits with a little plant-based protein in there and observe that your glucose increases to 124 mg/dL 30 minutes after you finish your meal. Within 90 minutes after your meal, it stabilizes at 90–95 mg/dL (close to your pre-meal baseline) and stays there for the next three…

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STEP 3: UNDERSTAND YOUR RESPONSES Now you get to have some fun and do some experiments! Yay! This is very exciting because you get to eat all kinds of foods and see what happens to your glucose levels. The key to these experiments is to make sure you accurately record and learn from them. In Appendix A, we’ve provided a place for you to write down your foods, your beginning, peak, and average glucose numbers, and the length of time it took to return to pre-meal baseline. You may wish to note any unusual factors that might have impacted the measurement positively or negatively, and your emotional state (feeling good, having negative thoughts, and your level of stress and/or fatigue, etc.).

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Test #1: The Roller Coaster Your first test will be to deliberately create high glucose levels throughout the day. This is to learn the extreme (I hope it’s extreme to you and not the norm!) of a real hyperglycemia spike and then a hypoglycemia low. This should be done on a rest day from training and competition, so that exercise doesn’t influence the results and you don’t end up ruining a critical training day. (Reminder: the results would be different if this was made on a training day.) For this test it’s important to allow sufficient time, roughly 90 minutes, depending on the meal composition, between meals and snacks to allow your glucose levels to return to the basal amount and see if you’re going to have any excessive drops in glucose levels at the bottom of the “roller coaster.” Once you feel like you’ve hit bottom, pre-meal baseline or even lower, then have your next snack or meal and go back to the top of the roller coaster again. Disclaimer: this is only for the purpose of testing and shouldn’t be done on a regular basis!

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