Working out on an empty stomach – Is it good for you?

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Medically reviewed by Kimberly Langdon, MD

working out on an empty stomach

Is working out on an empty stomach help you lose weight? This is a hot topic among exercise fitness enthusiasts. Exercising on an empty stomach, for some people, is just not an acceptable idea. Some approaches encourage you to exercise on an empty stomach first thing in the morning, usually waking up and rolling out of bed go-to workout in a fasted state.

Exercising on an empty stomach is also called fasted state, fasted cardio, or state of fasting[1]. British Journal of Nutrition[2] establishes and published a study content that those who exercise without eating burned fat nearly up to 20 percent faster than those who ate before workouts.

However, exercising in this way may not only make it less beneficial, because you do not have the energy necessary for a high-intensity workout, but your body also starts using the content of muscle mass to take stored energy fuel.

Research shows that for those including at least 30 percent of the protein[3] in their first meal, their body fat percentage is lower. Exercising when your body is dehydrated and without glycogen will make it more difficult to burn more fat. Without the energy of a healthy diet, your muscles will not have enough glycogen energy fuel for heavy workouts.

Is Working Out On An Empty Stomach Good? 

We can define an empty stomach in various ways. This means waiting a long time after eating before exercising to minimize digestive issues during exercise. For example, waiting at least 60 minutes to 90 minutes after a light meal can be beneficial before doing fasted cardio exercises like running.

Different people work well in different circumstances and decide whether someone should eat or what diet they should follow before fat-burning training, it depends largely on what works best for you.

While there is research[4] to support work on an empty stomach, this does not necessarily mean that it is ideal. Your body stores about 2,000 calories[5] as glycogen and much more in stored fat.

Most studies showed[6] no difference in performance between those who ate before high-intensity exercise that lasts less than an hour and those who did not.

In contrast, exercising on an empty stomach also has its downsides. By skipping a meal before strenuous activity, your stomach will not growl with hunger and it will also contract more easily.

Exercising while hungry can cause a dramatic change in your blood glucose, and can increase the chance that you may feel nauseated, dizzy, or lightheaded. You might even be fainting, which increases the risks of a fall or other serious injury.

Some research also points to another potential downside. If you don’t have food in your body, your body won’t necessarily start burning fat.

In a 2015 study[7], working out in the morning after a night sleep might increase cortisol levels. The study figured out that exercising on an empty stomach can have some undeniable drawbacks with your muscles.

Instead, your body may begin to break down muscle tissue leading to an overall, long-term loss of muscle mass.

In contrast, a study carried out by health scientists at the universities of Bath and Birmingham showed that by the timing of eating and exercising, people can manipulate their blood sugar levels.

This research is conducted in six weeks, with 30 men classified as overweight or obese. The result was compared between 2 groups: intervention groups (those who eat breakfast after workouts) and the normal groups (who do not change their lifestyle). People working out before breakfast can burn twice the fat amount as the normal group. This type of exercise didn’t affect weight loss, but it did improve overall health. Read to find out more about ways to lose weight effectively.

Benefits of Working out On an Empty Stomach 

Burn fat faster. 

When your body is in a state of fasting, your body fat is converted into energy. In one study[8], 12 active men who ran either after breakfast or while they are fasting from the night before were evaluated. It showed that starting your workout before breakfast could result in losing more fat without adding extra calories later.

Boost your body response to insulin. 

When your body is in a fasting state with an empty stomach, it causes a very wide range of hormonal activity. The most important are improved insulin sensitivity and increased levels of growth hormone for men and women.

When we eat, our body releases insulin[9] to absorb all the nutrients. One of the many health benefits of fasting, however, is it may reduce insulin sensitivity. With less eating, insulin is not released as often, so your body does not become resistant to the hormone.

Improve performances. 

Depending on the type of exercise you are doing, it may make sense to train on an empty stomach. There is evidence[10] that exercise when your carbohydrates are low, like when you are in a fasted state, actually may improve performance during routine, intense workouts.

Time-limited eating can help you lose weight. 

It’s the idea of working out on a fasted state with a time-restricted diet. In this diet plan, you can eat as much as you want of whatever you want.

working out on an empty stomach

What To Eat Before And After Working Out?

Whether it is better to eat before or after a workout, is presently unknown. Working out on an empty stomach is rarely a great idea because you cannot ensure that you have enough stored energy to get you through your workout.

Focus on healthy carbohydrates and protein-rich snacks before your workout to maximize muscle growth and strength.

There are some pre-workout meals/snacks that you can prepare, which are:

  • Peanut butter and banana toast (bananas also help raise potassium levels that are often depleted through sweat)
  • Appel peanut or almond butter
  • Milk and oatmeal
  • Whole-grain cereal
  • Yogurt.

After exercising, plan your post-workout meal 1 to 2 hours after. Also pay attention to protein, fat, and carbohydrate content as this will affect how your body and tissue repair.

Here are some examples of post-workout meals/ snacks.

  • Turkey sandwich with whole-grain bread and vegetables
  • Pork loin baked and red potatoes
  • Chicken breast and pasta
  • Salmon, green beans, and carrots
  • Oatmeal and peanut butter

Plus knowing what to choose before and after training will help you get the most out of your efforts. Here are some tips to have effective exercises:

  • Before doing fasted cardio, make sure that you eat a few hours before you exercise. Get used to doing gym two to three hours after a meal to make sure your stomach is empty, otherwise, you’ll end up with health complications[11]  such as diarrhea, and abdominal pain.
  • Another tip before working out is to determine which is the right training fitness for you to burn fat. This will contribute to greater success if the work performed is one that suits your body type and produces the needed strength.
  • The last tip for a healthy post-exercise is to drink plenty of water. Because your body loses a lot of water during your high-intensity workout, be sure to replace it and get more water to stay healthy.


Different people exercise well in different circumstances. If you do training sessions on an empty stomach at times, don’t’ sweat it, however, it may no longer be fine for longer-lasting and intense physical activities. You are your guide, so pay attention to your body, and do what feels best for you

If you think that you may pass out on an empty stomach during a workout session and feel like eating something, go ahead. Stay properly hydrated, eat a healthy diet, and maintain a lifestyle that aligns with your health interests. And always remember to discuss with your healthcare provider before starting a different exercise program.

Frequently Asked Questions

Is working out on an empty stomach an excellent idea?

Working with an empty stomach may not be the best idea for everyone. For every study that finds it easier to burn fat if you exercise before eating, there is another that claims the opposite.

How long after eating is your stomach empty?

It usually takes 4 to 5 hours[12] to empty your stomach after a full meal and a little less after a snack or liquid, but it depends on the amount and kind of food you ate.

What are the benefits of fasted cardio?

Fasted cardio training is done in a state of fasting, in which your body is no longer processing or digesting food. Benefits[13]  include lipolysis, fat oxidation increased, and decreased levels of insulin.

How does fasting exercise help you lose weight?

The idea behind “train low, compete high” is that working in a low glycogen state helps your body become more efficient at burning fat if, at a time when carbohydrate levels are high, the body is primed and pumped.

When should you eat?

The type of activity you do can help determine whether you should eat before your workout. For light exercise or low impact activities like walking, or gentle yoga, you may not need to eat beforehand.

Is working out on an empty stomach safe?

While there’s a study to support working out on an empty stomach, this doesn’t automatically mean it’s a great idea. When you exercise on an empty stomach, you may burn valuable energy sources and have not enough energy

+ 13 sources

Health Canal avoids using tertiary references. We have strict sourcing guidelines and rely on peer-reviewed studies, academic researches from medical associations and institutions. To ensure the accuracy of articles in Health Canal, you can read more about the editorial process here

  1. Hassane Zouhal, Ayoub Saeidi, Amal Salhi, Huige Li, Faadiel Essop, Ismail Laher, et al. (2020). Exercise Training and Fasting: Current Insights. Available from:
  2. Javier T. Gonzalez, Rachel C. Veasey, Penny L. S. Rumbold & Emma J. Stevenson. (2013). British Journal of Nutrition, 110, 721 - 732. Available from:
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  9. Stephen R Bird & John A Hawley. (2017). BMJ Open Sport and Exercise medicine, 2(1). Available from:
  10. Jonathan D. Bartlett, John A. Hawley & James P. Morton. (2014). European Journal of Sport Science, 15(1), 3-12. Available from:
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Healthcanal Staff

Medically reviewed by:

HealthCanal Editorial team is a team of high standard writers, who qualified the strict entrance test of Health Canal. The team involves in both topic researching and writting, which are under supervision and controlled by medical doctors of medical team.

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