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Intermittent Fasting And Working Out: Tips To Exercise Safely 2023

Mitchelle Morgan

Updated on - Written by
Medically reviewed by Kathy Shattler, MS, RDN

intermittent fasting and working out

A healthy and active lifestyle is something that many people seek. Among the best ways to eat fewer calories and lose weight is intermittent fasting. But is it possible to combine intermittent fasting and exercise?

You can combine this type of nutritional approach with exercise, but specific precautions are vital. This article looks into fasting and working out, different types of intermittent fasting, and creating an effective plan.

Can You Do Intermittent Fasting and Work Out?

Intermittent fasting has been around for some time, but fasting has been here for centuries. People have taken to this practice for health and spiritual reasons. However, today’s goal is to use intermittent fasting to lose weight.

Studies[1] show that you can use it to improve your metabolic rate and achieve weight loss. Plus, it’s also possible to work out while doing intermittent fasting. You can even develop an intermittent fasting workout schedule to give you a clear plan.

But, it’s crucial to be cautious when in a fasted state. Exercising on an empty stomach can pose a challenge for your body. You have to learn to listen to your body and not push yourself beyond what you can handle.

Usually, your body will use up carbohydrates to come up with glucose. The body stores any excess amounts of glucose as glycogen. Intermittent fasting aims to use up these glycogen reserves, thus achieving weight loss. Many health benefits come with having a healthy weight. One way of achieving better results is engaging in fast workouts. Researchers studied two groups[2] where one engaged in fasted exercise while the other only did intermittent fasting. The group that took part in fasted exercise achieved more weight loss. Researchers concluded that more fat was burned doing exercise in the fasted state as opposed to the fed state.

Workout While Fasting: Pros vs. Cons

Intermittent fasting combined with exercise is beneficial[3] to your body by helping to manage blood sugar levels and maintain low blood pressure. It’s crucial for people with insulin sensitivity problems since exercise reduces insulin resistance in the body.

In addition, eating fewer calories leads to weight loss since the body burns fat. Glycogen stored in the body becomes the main fuel source when reducing carbohydrate intake.

But, be cautious with working out and intermittent fasting since this can start breaking down your muscle. Plus, you end up with less energy hence the need for less intense exercising.

Safety Tips to Exercise During Fasting

Exercise is important when you want to build muscle mass and reap rewarding health benefits. It’s one of the proven ways to prevent ill health. But, when you engage in intermittent fasting while working out, you can burn more fat.

Still, like any other fitness quest, doing it the right way yields results. Below are some safety tips for exercising while fasting.


While you lower your daily calories by fasting, you must remember to drink lots of water. Hydration must be at the top of your to-do list when you plan to exercise while fasting. While not taking in more energy, combining fasting and exercise while dehydrated[4] is dangerous.

Fasting helps you by burning fat, and exercise benefits you to gain muscle and burning calories. But, remember to drink water as you take part in fitness exercises like walking, yoga, or going to the gym.

Lower Workout Intensity and Duration

When you start intermittent fasting, you must reduce daily calories for the fasting period. It’s possible to exercise on an empty stomach, but the intensity can’t be the same. The best thing to do is lower the workout intensity and duration.

For instance, you can try doing fasted cardiovascular (cardio) exercises or other fasted workouts which are less demanding. Listen to your body when in a fasted state and exercising. Engaging in intense activities like lifting weights for long durations, intense cardio sessions, or going to the gym can be hazardous.

You need lots of energy even to engage in brisk walking or long yoga sessions. All these can help you[5] burn more fat, but pushing yourself too hard can cause you to feel light-headed and may precipitate low blood pressure and dizziness. Imagine the risk of that happening while lifting weights at the gym.

Focus Less on Increasing Muscle Mass

Intermittent fasting effectively reduces body fat, but it’s not the best if the goal is to build muscle. In fact, you should not focus on muscle gain while fasting because you’re eating less. While working out, a good intermittent fasting program helps burn fat but not gain muscle. Intermittent fasting and muscle gain may not work together.

Muscle gain requires eating lots of calories over a longer period, but that’s impossible in a small 8-hour fasting period. Intermittent fasting is an effective way to lose weight since your eating window is smaller.

Therefore, if your purpose is to build muscle mass, opt for another plan. When you want to build muscle and burn body fat, weight lifting is a great exercise[6]. But, it requires lots of energy to do, so it’s better to start lifting weights after you eat if you must do so. Other fitness exercises like cardio might be better while fasting.

Eat a Meal Close to an Intense Workout

An intermittent fasting workout plan is all about the exercise time—exercise a little after eating your meal, especially for intense sessions. You might feel dizzy if you workout during your fasting period, so wait until you’ve eaten.

For this to work, timing is everything. Figure out the exercises you want to do, like cardio sessions, lifting weights, or going to the gym. These require lots of energy, and it’s not safe to do so on an empty stomach.

Therefore, plan to do any intense workout when you’re not in a fast state. But, if you want to fast and work out, you can try walking or yoga. These are good, especially for intermittent fasting and working out in the morning.

Have a Plan

Intermittent fasting is effective when it comes to weight loss. But, if you choose to combine it with exercising, you have to come up with a plan. The key to a good workout session is to have the energy to complete it.

So, think about when you want to exercise and time your eating period. For instance, if you engage in fasted cardio, you have to time your eating period right after the exercise. It’s better to do so and also to listen to your body.

Still, if you prefer doing less intense workouts like simple aerobic exercise, you can do so anytime. That means you can work out during the fasting period or when it’s over. The most important thing is doing safe workouts while fasting.

In addition, having a plan means knowing which workouts to do, when and at what time. Fasting and exercise can be fun if you vary your workouts. It’s the best way to benefit from your fitness journey.

Have Some Electrolytes

Effective intermittent fasting requires not taking any food or drink that will break the fast. However, it’s important to keep your electrolytes up. Electrolytes are crucial when engaging in intermittent fasting workouts. So, you can take a natural sports drink or coconut water, but not any sugary drinks.

Food is the main source of electrolytes for the body, but the amount gets lower when fasting. You need electrolytes to keep your energy levels up when taking part in fasting and exercise. So, have some when you want to exercise in a fasted state.

Time to Work Out During Intermittent Fasting

Fitness can benefit you in many ways, including preventing certain adverse health conditions. You can enjoy many health benefits when you work out with intermittent fasting. There are numerous exercises you can do even in a fasted state.

However, it’s important to have a schedule that dictates your time—working out while fasting can happen during the fasting or eating period. Therefore, think through your timing for effective results and health benefits.

There are fast workouts that you can do that are less intense such as home cardio sessions. However, save things like lifting weight and intense aerobic exercise for the eating window. In fact, if your goal is to build muscle, fasting might not be for you.

Intermittent fasting can impact building muscle since you’re eating fewer calories. It’s even possible for you to experience[7] intermittent fasting and muscle loss. Therefore, keep that in mind when considering any type of fasting weight loss regimen.


Intermittent fasting is among the most effective ways to lose weight and achieve your body goals. The good news is that you can engage in fasting while working out. Intermittent fasting while engaging in an exercise program helps you achieve better results since you are burning more calories. 

However, it’s important to note that working out while fasting requires caution. You have to exercise safely, especially in a fasted state when you have less energy. While exercise helps with weight loss, be less focused on building muscle when fasting.

+ 11 sources

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  1. Botterman, L. (2022). Research review shows intermittent fasting works for weight loss, health changes  | UIC Today. [online] Uic.edu. Available at: https://today.uic.edu/research-review-shows-intermittent-fasting-works-for-weight-loss-health-changes.
  2. ‌Vieira, A.F., Costa, R.R., Macedo, R.C.O., Coconcelli, L. and Kruel, L.F.M. (2016). Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: a systematic review and meta-analysis. British Journal of Nutrition, [online] 116(7), pp.1153–1164. Available at: https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/effects-of-aerobic-exercise-performed-in-fasted-v-fed-state-on-fat-and-carbohydrate-metabolism-in-adults-a-systematic-review-and-metaanalysis/0EA2328A0FF91703C95FD39A38716811.
  3. ‌Grajower, M.M. and Horne, B.D. (2019). Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus. Nutrients, [online] 11(4), p.873. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6521152/.
  4. ‌Leiper, J.B., Molla, A.M. and Molla, A.M. (2003). Effects on health of fluid restriction during fasting in Ramadan. European Journal of Clinical Nutrition, [online] 57(S2), pp.S30–S38. Available at: https://pubmed.ncbi.nlm.nih.gov/14681711/.
  5. ‌Cox, C.E. (2017). Role of Physical Activity for Weight Loss and Weight Maintenance. Diabetes Spectrum, [online] 30(3), pp.157–160. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5556592/.
  6. ‌Thomas, M.H. and Burns, S.P. (2016). Increasing Lean Mass and Strength: A Comparison of High Frequency Strength Training to Lower Frequency Strength Training. International journal of exercise science, [online] 9(2), pp.159–167. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4836564/.
  7. ‌Tinsley, G.M. and La Bounty, P.M. (2015). Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition Reviews, [online] 73(10), pp.661–674. Available at: https://pubmed.ncbi.nlm.nih.gov/26374764/.
Mitchelle Morgan

Medically reviewed by:

Kathy Shattler

Mitchelle Morgan is a health and wellness writer with over 10 years of experience. She holds a Master's in Communication. Her mission is to provide readers with information that helps them live a better lifestyle. All her work is backed by scientific evidence to ensure readers get valuable and actionable content.

Medically reviewed by:

Kathy Shattler

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