Many people believe that exercising on an empty stomach first thing in the morning enhances fat burning. Studies by Dr. Len Kravitz, exercise science researcher at University of New Mexico have shown the opposite effect occurs and test subjects actually burn more calories and fat under fed conditions. Fabio Comana, an instructor of exercise and nutritional sciences at Sand Diego State University states in his lectures that fasted cardio slows our ability to utilize fat as fuel and causes other detrimental effects in our bodies.
What Happens In our Body:
While we sleep our liver glycogen stores are depleted which triggers the release of cortisol. Exercising in the morning with elevated cortisol causes 4 things:
- A decrease in metabolism until food is eaten.
- The breakdown of muscle tissue to manufacture glucose for energy.
- A decrease in blood pH which causes acidosis. To manage acidosis our body has a reduced capacity for higher-intensity exercise.
- Reduced levels of serotonin and dopamine in the brain which are associated with higher levels of anxiety and depression.
To maintain our optimal metabolic rate (reduce cortisol) and restore liver glycogen levels that have been depleted through the night, our body only needs a small amount of carbohydrate and protein. Eating a small snack with 20-25g of carbohydrate and 5-10g of protein is sufficient (equal to about 150 calories) to restore our metabolism and maintain our hormonal balance.
Afternoon & Evening Exercisers:
We will be able to exercise harder and burn more calories if we eat before working out. Starting a workout with low blood sugar will cause us to fatigue earlier than if we snack prior to working out. However, we will not want to workout on a full stomach so eating a snack at least 45 minutes prior to exercise is ideal. How much you choose to eat will depend on your body and your digestion. A good guide for a pre-workout snack is about 200-250 calories.
Pre-Workout Snack Ideas:
When choosing a pre-workout snack, we need to remember that protein does NOT give us energy. Carbs fuel our muscles and our brain and protein repairs the muscle tissue. Fats provide a slower release of energy as they are calorie dense and take longer to digest. Choose a carbohydrate snack mixed with a little fat and protein. Here are some suggestions:
- Apple slices with nut butter
- Banana with nut butter
- Celery with nut butter
- Greek yogurt parfait with fruit
- Greek yogurt parfait with granola
- Oatmeal with crushed flaxseed
- Grapes and almonds
- Whole food is the best but if you are in a hurry and need to grab a granola bar use this suggestion – Around 200 calories, at least 4g protein, no more than 7g sugar
- Trail Mix – use superfoods like Golden Berries, Dried Goji Berries, Dried Cranberries
- Peanut Butter Protein Balls