Many people fast during exercise due to various reasons, including religious commitments, blood work, timing of exercise or because they might suffer gastrointestinal issues.
Fasting during exercise can be beneficial if done safely. If you exercise while fasting more than once a week, first check with your physician and come up with an individualized plan together.
The American College of Sports Medicine recommends that more than 250 minutes per week of exercise is required to provide clinically significant weight loss. This may be physically demanding for some, especially if energy is low.
Registered dietitian Brittanie Volk suggests that a snack approximately one hour before exercise that is low in fat and moderate in carbohydrate, fiber and protein may help you exercise longer and at a higher intensity.
Chronic fasting can lead to dehydration, loss of nutrients, dizziness and low energy. If you superimpose a stressor on the body, you increase your risk of heat-related illness, injury and other problems. Fasting limits the energy available to fuel your body. Glycogen, a main source of fuel, is used on a cellular level for brain function; therefore, a reduction in it not only affects your muscles, but can lead to an altered mental state.
"Nutritional recommendations are never that simple," Volk says. "Everyone is unique, so you may have to experiment to determine what's best for you."
If you feel any of these symptoms, please cease exercise and seek medical attention if they do not improve immediately upon stopping.
- Severe breathlessness
- Lightheadedness or dizziness
- Loss of sight or hearing
- Loss of muscle control or fatigue
- Nausea or vomiting
- Excessive perspiration
- Excessive lethargy or fatigue