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Sport and Insulin Resistance
Sport and insulin resistance: How can you have enough energy to exercise without raising your blood sugar? This article will answer this question.
Physical activity is particularly beneficial for people with insulin resistance or prediabetes. Carbohydrates are the main source of energy for muscles, but can also contribute to raising blood sugar levels. So how can you eat to have enough energy for exercising without affecting your blood sugar control?
Isn’t Sugar Bad?
The World Health Organization (WHO) recommends limiting the consumption of added sugar. Excessive sugar consumption can have negative effects on weight, blood sugar control, and heart health. However, during long-term or high-intensity exercise, simple sugars are essential for optimal performance. When participating in endurance events (e.g. a half marathon), blood sugar levels below a certain threshold will negatively affect performance. The best way to keep these levels high is to use fast-acting sugars (also called simple sugars) like sports drinks and gels. The good news is that it will not harm one’s health or blood sugar control, since they are being used as fuel during exercise.
Will Eating Carbs Raise My Blood Sugar?
Several factors can influence blood sugar levels, including diet, stress, sleep, and exercise. For example, when sugar is ingested during exercise, there are few or no “spikes” in insulin or glucose. However, when carbohydrates are consumed outside of exercise, it is normal for blood sugar levels to rise. Transient changes in blood sugar concentration in response to a food or a meal should not be confused with chronically high blood sugar levels. Moderate “spikes” in blood sugar levels are normal, while chronically high blood sugar levels indicate prediabetes or diabetes. After ingesting carbohydrates, insulin is released to help the body remove glucose from the blood. The insulin “spikes” that we see in healthy individuals are there to help the body store glucose in the appropriate tissues. Chronically high blood sugar levels develop because insulin becomes less effective. Glucose concentrations stay elevated longer, especially when someone is inactive. This is why active people with insulin resistance should control their portions of carbohydrates when not exercising.
What About Continuous Glucose Monitors (CGMs)?
CGMs are tools that provide real-time blood sugar levels measurements. While they were previously used mainly among diabetics, their popularity has exploded in recent years, both among athletes and people who are health conscious. These tools can be useful in various ways, for example to avoid hypoglycemia during exercise, to optimize your diet pre-workout, to better understand your individual glycemic response to different foods, and to assess your blood sugar levels during sleep. However, they also have limitations, and their data can easily be misinterpreted.
One of the most common myths is to think that you should avoid all foods that cause a sugar “spike”. Some people will notice a big upswing in their blood sugar levels after eating certain foods that are high in carbohydrates. You need to remember that this is a normal physiological response as explained previously and that many other factors can influence this result. If you notice that your blood sugar levels increase with a certain food, for example oatmeal, you should check to see how reproducible the result is and also to test the other components of the meal. For example, if you eat instant oatmeal with almond milk, blood sugar levels can rise much faster than if you eat still cut oats and add protein or fat like nuts, seeds, or yogurt. Additionally, eating the same food at a different time of the day, or after a workout rather than before, can make a huge difference. Avoiding certain foods will likely mean that you will replace them with something else, and that replacement may or may not be a healthier choice. For example, a low-carb, high-fat diet can sometimes be harmful for heart health.
Author
Kathryn holds a Bachelor Degree in Nutrition as well as a Bachelor and a Master Degree in Kinesiology, all from Laval University. She is a Registered Dietitian and active member of the Ordre professionnel des Diététistes Nutritionnistes du Québec (ODNQ) and of the American Academy of Nutrition and Dietetics. She holds the Monash University's certification for the FODMAP diet and IBS, and has considerable clinical experience in that area. She is also an accomplished athlete, having ran track and cross-country at a national level. Kathryn specializes in sports nutrition, weight loss, diabetes, as well as heart and gastrointestinal health.
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