Many athletes and adults interested in body fat loss believe that early morning exercise in the fasted state (no pre-exercise breakfast) can accelerate the loss of body fat beyond that of cutting back on calories for the day or the week. A recent study compared changes in both fat and fat-free mass in young women following a hypocaloric diet. Healthy young women performed early morning exercise in the fasted or non-fasted state for four weeks each. They followed a customized dietary plan designed to create caloric deficit. A meal replacement shake was provided immediately before (fed) or immediately after (fasted) the morning workout. Both groups of women lost a significant amount of weight and body fat, but there was no difference between the two groups. They lost weight because they were exercising and cut back on calories- not because they skipped breakfast before working out.
So is skipping breakfast or an early morning snack worth the trouble? It probably depends on both you and your workout. Often athletes skip an early morning feeding because of time and convenience. But what if your workout is higher intensity or longer duration- basically, just a tough workout? These results indicate that weight and body fat loss associated with exercise and calorie restriction are similar regardless of whether early morning exercise is performed with food intake beforehand or with no food beforehand. So it might be worth it to actually provide your body with fuel needed to complete the type of workout scheduled in your training program. When you wake up in the morning, your liver carbohydrate stores are low, and this can impact your blood sugar levels. Blood sugar is one of the fuels that you use during exercise, and is the fuel that your brain uses- helping with focus and concentration. If you are worried about having food in your system so close to exercise, you can consume liquids and small amounts of easily digested foods. If you want to lose weight or body fat, it might work best in terms of energy levels to decrease calories at dinner or later in the evening.
Monique Ryan is a Certified Specialist in Sports Dietetics with over 25 years of experience helping active people optimize their nutrition and body composition. Contact us at 847-864-8689 to schedule your consult. Ryan has worked with elite athletes in soccer, football, basketball, triathlon, cycling, and mountain biking.
She is the author of Sports Nutrition for Endurance Athletes, 3rd edition.