Exercise is an essential component of a healthy lifestyle. Sometimes, you may have to approach exercise with caution. Abstaining from food and drink for a set time — a practice known as fasting — is one of those instances.
Fasts vary; some last only a few hours and others span weeks.
Spiritual fasting practices such as Ramadan, specify that eating and drinking can take place only during set times (dusk to dawn) throughout the month, according to the Academy of Nutrition and Dietetics. Fasting during Navratri and Karwachauth lasts for a day or more than a week. Other than that is intermittent fasting, done for health or weight loss reasons.
Some of these fasting types may not mix well with exercise. In particular, fasts that stretch 24 or more hours, fasts in which you’re restricting calories and nutrients (such as a juice cleanse), and fasts where you’re not drinking any water are types of fasting during which exercise is unsafe.
Things to Keep in mind while exercising during Fasting
For anyone fasting and planning to exercise, it’s important to keep in mind that low-intensity and short-duration workouts are better options than longer or high-intensity workouts.
You can use the rating of perceived exertion (RPE) scale to help you gauge your intensity. Rate of perceived exertion (RPE) is a way to measure the level of exertion a person feels during physical activity.
The RPE scale runs from 0 to 10, where 0 corresponds to how much effort it takes to sit in a chair (none), and 10 is the effort it takes to complete an exercise stress test or other difficult activity (very heavy)(www.everydayhealth.com/). Aim for an effort level of 4 (somewhat heavy) or lower while fasting. Activities such as walking, cycling, swimming, yoga, and Pilates are all great options.
Tips for Working Out if You’re Fasting
Exercising while fasting can be risky. If you’re taking medications, have health conditions like coronary artery disease, hypertension, or diabetes, or have another health issue that may interfere with your ability to safely exercise (or safely fast), talk with your healthcare provider before working out and fasting simultaneously.
If you want to exercise during a fast, follow these tips for a safer, not to mention more comfortable, experience.
- Watch your intensity. To conserve energy for the rest of your day, stick to lower-intensity workouts while fasting, especially if you’re exercising at the beginning or midway through your fast. Aim for an exertion level no higher than a 4 on a scale of 1 to 10, where 1 is resting and 10 is maximum intensity.
- Keep it short. Doing a low-intensity activity for long enough can make for a higher-intensity workout. That means going for a three-hour walk while fasting may not be a good idea, even if the walk is low-intensity. If you normally work out for 30 minutes or an hour at a time, stick to the low end of that time frame if you’re exercising while fasting.
- Stay hydrated. Drink plenty of water while fasting (if possible) and check your urine to gauge how hydrated you are (or aren’t): The darker the color of your urine, the more dehydrated you are. He adds that a minimum of eight glasses of water is recommended.
- Exercise at the beginning. If your schedule allows, try to work out toward the beginning of your fast. As you’ve recently eaten, your body still has plenty of stored nutrients to fuel the workout. This may make exercise more manageable than if you try to work out toward the end of your fast when your body is depleted of nutrients.
- Don’t overdo it. Pay attention to your body’s signals, and stop exercising if you feel nauseated, light-headed, or have a headache, Wirtz says. You may also want to replenish with a small snack.
It’s important to eat a well-balanced diet once the fast is over.
Benefits of Fasted Workouts
In the state of a fasted workout, insulin sensitivity increases and so does the production of growth hormone. Both of these can boost fat loss, which supports the argument that fast exercise results in more fat loss.
The advice to train in a fasted state is a strategy to increase fat burning, with the hope of using some stored fat. For those who practice intermittent fasting, training on an empty stomach can be more convenient because you may have more time available in your schedule during your fasting period.
Drawbacks of Fasted Workouts
The intensity of the exercise you are doing affects whether your body uses fat or glucose as energy fuel. Heavy lifts or fast running will use stored muscle glucose (glycogen) more than fat, whether or not you are doing these tough workouts on an empty stomach.
When you exercise too intensely in a fast state, your muscles can degrade. This is because your body pulls apart amino acids to help preserve critical blood glucose. Also, chronic low blood glucose and rising cortisol (stress hormone) levels can depress the immune system.