Does Working Out Break Your Fast?

If you’re trying to improve your fitness by working out while fasting, you might be wondering if you’re doing more harm than good. Here’s what you need to know.


Many people practice intermittent fasting which involves regularly fasting for a set period of time, typically 16-24 hours. Intermittent fasting has been touted as a way to improve overall health, including promoting weight loss and increasing longevity. However, one common question is whether exercise can be performed while practicing intermittent fasting without breaking the fasted state.

This article will explore the effects of exercise on a fasted state and any potential benefits or drawbacks associated with engaging in exercise while in a fasted state. It will also provide key information on how to maximize fat burning during fasted workouts. This article provides an overview of the effects of exercise on fasting and helps you to decide if working out during a fast is right for you and your fitness goals.

What is Intermittent Fasting?

Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating, with no set rule as to what macronutrients and how much food should be consumed during the “eating” times. It is a type of diet that has become increasingly popular in recent years, as it has been associated with numerous health benefits such as weight loss, increased energy levels and mental clarity. Proponents of intermittent fasting state that it helps to improve insulin sensitivity and reduce inflammation.

IF protocols generally require fasting for a certain period of time (anywhere from 12-24 hours) and then eating whatever foods they’d like over a designated window of time (typically 4-8 hours). During the fasting period, individuals may choose not to eat anything at all or consume certain types of drinks like black coffee or tea without added cream or sugar. Although there are numerous variations of IF protocols when it comes to working out while fasting, many experts suggest that workouts should be avoided during the fasted period so as not to compromise results.

What is Exercise?

Exercise encompasses any physical activity that makes your body work. Depending on intensity, type and duration, exercise mobilizes different energy systems in the body and helps to improve physical function or performance. Exercise is overall beneficial for both mental and physical health.

However, there are a variety of factors that can influence whether or not working out while fasting is safe or effective. These include the type of exercise being performed, the goal of the fasting period, intensity of exercise, duration of the fast and other personal factors such as age and gender.

When it comes to interval training and weightlifting, which are both high-intensity exercises that involve anaerobic activity (activity in which oxygen is not integral to ATP production), a shorter fast may be required depending on the goal one wishes to achieve. Whereas someone participating in a moderate form of exercise such as walking or yoga might be able to extend their fasting timeline without any problems.

Overall, it is important to note that whether you choose to work out during a fast does depend on many factors and needs to be considered for each individual’s unique situation before deciding if it’s right for you.

Does Exercise Break Your Fast?

Exercising while fasting is a hotly debated topic, as some people believe that it can break your fast and undo all the progress you’ve made. But is this really the case? In this article, we’re going to look at the pros and cons of working out while fasting as well as how it can impact your overall health and fitness. So, let’s dive in and take a closer look at the potential effects of exercising while fasting.

Exercise Intensity

The intensity and type of exercise that you do while fasting may influence whether the energy expended is coming from your fat stores or the food in your stomach. Generally speaking, lower intensity activities such as walking and yoga have minimal effect on your fast, while high intensity workouts such as circuit training and running at a steady pace do break your fasts.

If you are doing moderate to high-intensity exercises during a fasting period, it is important to consider how this may affect the duration and success of your diet. The body adapts to exercise differently depending on whether it is in a fed or fasted state; when fed, the body will use glucose to fuel activity quickly. When fasted, it must rely on stored body fat for energy. Therefore, depending on the length of time that you were fasting before exercising, you may be burning through fuel (and calories) quicker than anticipated or desired.

It is recommended that if you are fasting before exercising that you try low-intensity aerobic exercises such as walking or light jogging instead of high-intensity exertions like HIIT or CrossFit so as not to compromise too much energy out of stored fat stores – helping ensure the success of your diet efforts. Additionally, make sure to stay well hydrated throughout this process by drinking plenty of water; dehydration can reduce performance as well as increase feelings of hunger long after exercise has ended.

Type of Exercise

The type of exercise you choose can also have a significant impact on how your fast is affected. Generally, high-intensity interval training (HIIT) and resistance exercises (such as weight training and calisthenics) can require more energy than aerobic activities. As such, these types of workouts may demand more calories to fuel them, which means that your body needs to resort to breaking down fat stores rather than relying solely on the existing energy stored in your muscles. High-intensity activities such as circuit training or running at a fast pace carrying weights will increase the rate at which your body burns both fat and carbohydrates during the activity, meaning it could break your fast before it would normally end.

On the other hand, low-intensity activities such as yoga or slow-paced walking are not likely to break your fast since they are done at a constant pace without spikes in energy demands. This is because low-intensity exercises rely primarily on the energy stored within muscles rather than any additional calories coming from food sources. Thus, low-impact exercises can help prevent you from breaking your fast prematurely if done for a short duration or with light intensity.

Benefits of Exercising While Fasting

Exercising while fasting can offer a variety of potential benefits and can be tailored to meet specific lifestyle and health goals. Here are some advantages that might be experienced from exercising during a fast:

1.Improved Weight Loss: As your body enters fasting mode, it starts breaking down fat for energy, which is beneficial for weight loss efforts. Incorporating gentle exercise into your fasting period can help speed up the process!
2.Reduced Appetite: Exercising while fasting can help control your hunger levels naturally, aiding in better portion control and food choices throughout the day.
3.Boosted Energy Levels: During prolonged periods of exercise while fasting, your body will burn through the stored glucose and start using fat as an energy source. This helps you stay energized during intense workouts and activities over time!
4.Stronger Immune System: Giving your body time away from food allows it to re-focus on other important things like maintaining a strong immune system and producing more antioxidants, something that will serve you well in times of need!
5.Better Mental Health Benefits: Research has shown that working out on an empty stomach helps reduce stress hormones that may lead to anxiety or depression if left unchecked. Additionally, exercising can create those pleasant “happy hormones” like endorphins or serotonin which make us feel good!

Risks of Exercising While Fasting

Fasting is a health practice that has gained traction in the last few years and can be an effective way to lose weight, detoxify the body, and generally improve health. Exercising on an empty stomach or during a fast carries a certain set of risks, however, that should be considered before beginning to work out while fasting.

For starters, exercise can cause low blood sugar levels due to increased energy usage. Low blood sugar can impair muscle functioning and have negative effects on your overall performance. If you’re engaging in high intensity workouts while fasting, low blood glucose levels may occur quickly which could lead to dizziness or lightheadedness as well as potential overheating due to lack of proper hydration.

When working out while fasting it’s important for you to consider the duration of your fast relative to the type of exercise you are engaging in — long cardio sessions may be dangerous if your fast has extended beyond 24 hours since your body will not be able received enough energy from stored carbohydrates and fat sources alike during fasts longer than 24 hours due to decreased available blood glucose levels. However all types of exercise – from running and lifting weights to yoga – carry some risk when done under extreme conditions like during a long-term fast or without properly hydrating yourself with water beforehand. It’s important for you to listen closely to your body as well; if you begin feeling unusually weak or lightheaded then stop exercising immediately and take steps towards rehydrating yourself by drinking water and eating a snack containing some carbohydrates if possible.


In conclusion, exercise does not necessarily have to break your fast. It all depends on your level of exertion and how you are breaking the fast. If you perform light-to-moderate exercise and have a light meal to break the fast (with protein-rich foods, a moderate amount of fat, and some carbohydrates), then it is possible to do exercise without breaking the fast.

On the other hand, if you are performing strenuous workouts, such as HIIT or weight lifting, then it may be beneficial to break your fast with some carbs beforehand. This will give your body an energetic boost to help maximize performance. Additionally, after performing an intense workout session, try breaking the fast with a meal that contains at least 20g of protein along with some healthy fats and carbohydrates – this will aid in muscle recovery and growth!

Overall, when it comes to determining if working out breaks your fast – there is not one definitive answer but rather several variables which depend on your fitness goals & lifestyle. With careful consideration & proper nutrition planning, however – there is no reason why you can’t create a balanced approach to incorporating physical activity into fasting that works for you!

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