People believe cortisol is a fat storing hormone. In fact cortisol is actually a stress hormone. It is made in the adrenal glands from cholesterol contained in the fats you consume in your diet. Cortisol is released in response to epinephrine secretions when the body undergoes stress. For example, when you are scared and need energy to escape danger. Cortisol does in fact keep you alive; you cannot live without it. The common fear about cortisol is that if you have very high levels, then you are going to gain fat. This is absolutely true for individuals who undergo chronic stress.
Cortisol, Insulin, and Carbs Around a Workout
First of all, cortisol and insulin are hormones with opposite functions. Cortisol is very catabolic, meaning its chemical reactions break things down. Insulin is very anabolic, meaning its chemical reactions build new compounds. When talking about workout nutrition, there are a few ways to manipulate your hormone levels with carbohydrates to help you reach your goals. Now if you experience chronic stress, are trying your hardest to get lean, and are not making progress, then cortisol levels may be too high. That’s where carbohydrates come to the rescue. Eating carbohydrates before every workout will cause insulin to increase and cortisol to go down. The key is to lower cortisol chronically, not just a few times a week, so be consistent with the timing of your carbohydrates especially before, and after workouts. Combining the carbs with protein will maximize the benefits of your workouts.
Now let’s say you are trying to build muscle. When you workout really hard and break down muscle tissue. During that workout your cortisol levels increase and shut off insulin. Carbohydrates are beneficial here because they shut off cortisol by increasing the insulin. This will help preserve muscle tissue already being stressed, and the anabolic effects of insulin will help build new muscle and can even prevent soreness. To manipulate these hormones it is recommended to consume carbs and protein before, and after every workout. If you are working out for a long time, then you could even consume carbs during exercise to prevent breakdown of tissues.
The big question is how many carbs are required to produce this effect? The answer depends on the individual. In general the average person only needs between 15-25 g of carbs to lower cortisol at any given time. This is a huge difference from the recommendation of some to consume 100-200 gs pre or post-workout. For example, 100-200 gs of carbs is equivalent to 4 -7.5 medium sized bananas. Its simply more than you need.
When you exercise your body produces energy from fats, carbs and protein. Those are your normal energy yielding macronutrients. Let’s say you burned 250 calories according you your heart rate monitor. How do you know where that 250 calories came from? It is nearly impossible to burn 100% carbohydrates. If you assume the 250 is purely from burning carbs that would only be about 62.5 g of carbs; still way under the 100-200 g recommendations. In reality we burn about 40-50% carbs while exercising, which brings the carb expenditure down to 25- 31.25 g. This is much closer to the 15-25 g ranges for the average person. Keep in mind a larger person with more muscle mass requires more carbs because they burn more fuel overall.