Does Fasting Benefit Body Composition?

Fasting dates back to the earliest texts of many religions — it’s a part of almost every Eastern and Western philosophy or theology. There’s clearly something beneficial about it when it comes to spirituality for most, but does it benefit your body’s composition and overall health?

The Three Branches of Fasting

Fasting is defined as the process of abstaining from all or some kinds of food or drink, while the most commonly referred to version of fasting is intermittent fasting. Intermittent fasting can be grouped into three categories: alternate-day fasting, whole-day fasting, and time-restricted feeding. Whole-day fasting occurs if someone fasts for an entire day. When someone chooses to fast like this, they may practice fasting one or two days a week.

Perhaps the most heavily studied version of fasting is alternate day fasting. Someone practicing alternate day fasting may normally eat on Monday before fasting Tuesday.

Lastly, time-restricted feeding is a common version of fasting because many religions practice it. Intermittent fasting is typically thought of in this context, because it involves fasting for a specific time period. The most practiced form of time-restricted feeding is the 16:8 method. Someone practicing this method would fast for 16 hours a day, meaning they would choose an eight-hour window to eat and drink. Many people choosing time-restricted feeding will eat and drink between 11 AM to 7 PM or 12 PM to 8 PM.

a plate with the silverware positioned to look like the hours, minutes, and seconds hands of a clock

What Are the Body Composition Benefits of Fasting?

Intermittent fasting is one of the most beneficial types of fasting, so it’s relationship with body composition has been heavily researched in the past 12-14 years. Stark’s own Amir Mofidi says, “I’ve seen literature where there are two to three days of caloric restriction during fasting, and still no muscle loss. Intermittent fasting has been shown to preserve muscle mass across all the different versions — alternate-day, whole-day, and time-restricted. Muscle mass isn’t going away, and it’s still showing body fat reduction.”

This study compiled much of the available research on the subject and concluded that intermittent fasting can reduce body weight and body fat. Alternate-day fasting exhibited reduced body weight (by 3%–7%), total cholesterol (by 10%–21%), and triglycerides (by 14%–42%) in normal-weight, overweight, and obese humans.

4 identical meals are prepared in advanced for healthy, convenient meals during a busy week

Which Type of Diet is Best?

Amir says that the most beneficial type of diet is one where there’s a consistent, controlled environment. There is not a singular diet that is one-size-fits-all. Here’s the thing: you will find that your body composition improves if you choose a diet you will stick to. Whether it is intermittent fasting, paleo, keto, high carb, or low carb — your body composition will improve if you stick to a diet pattern.

Nutrient timing matters very little when compared to nutritional content. Being in a caloric deficit and eating high protein will lead to body composition results whether the meals are eaten in an 8-hour window, or throughout the day over 6 small meals. The timing of food should be based on what works best for your lifestyle.

Amir says, “Some groups might experience more energy with certain diets — like, oh, I have so much more energy when I skip breakfast. Someone else might be like, I have no energy — that’s where the sports performance can get dinged when trying to intermittent fast versus eating throughout the day.”

When it comes down to it: listen to your body and choose a style of fasting that works well for you.