Muscle Evolved

Does Fasting Stunt Growth?

By Zac Hyde · · Updated

Contents

Bulking is the act of purposely increasing the number of calories you consume to grow your muscles.

This process works best alongside a consistent strength training routine, which gives your muscles the signal to grow.

Many lifters who bulk eat multiple meals during the day to stay in a modest calorie surplus. How fast you can gain muscle varies a lot with training experience, age, sex, and genetics.

However, this begs the question of whether fasting stands as an obstacle in the way of muscle growth.

In this article, we will discuss the relationship between fasting and muscle hypertrophy in adults and see how they affect each other.

A quick note first: this article is about muscle growth in adults. Children and teens are still growing, so they should not follow fasting diets unless a doctor recommends and supervises it.

How does fasting affect muscle growth?

People often believe that fasting is synonymous with weight loss. In reality, some lifters use intermittent fasting while trying to maintain or build muscle. Some modifications are necessary, though.

"How is that possible?" I hear you asking.

Well, the main concept is quite simple.

Bulking to build muscles is all about eating enough calories and protein to support the muscle-building process.

Intermittent fasting, such as time-restricted eating, limits when you eat. It does not, by itself, set a calorie target or ban a certain food or macronutrient.

With that said, many people end up eating less and losing weight, since it is harder to eat more calories than your body needs in a short window (e.g., 8 hours).

The research so far is reassuring for adults who lift. In an 8-week trial of resistance-trained men, a 16/8 eating schedule kept fat-free mass and strength similar to a normal schedule while cutting more fat, per the 2016 study in the Journal of Translational Medicine.

A 2024 meta-analysis of seven trials found the same pattern: time-restricted eating plus resistance training lowered fat mass without a significant effect on muscle mass or strength. The studies were small and short, though.

Keep in mind that those studies mostly show muscle being maintained. If your main goal is to gain as much muscle as possible, a fasting window makes eating enough harder, but not impossible.

Here are some tips to help you grow your muscle mass while fasting:

  1. More calorie-dense foods

The vast majority of people on a weight loss diet avoid calorie-dense foods. For the purpose of muscle growth, they can help.

Healthy fats such as nuts, nut butters, olive oil, and avocado are useful, since fat contains 9 calories per gram, while protein and carbs have about 4.

  1. Diversify your meals

You don't have to live on plain chicken breast and brown rice during the bulking phase.

Variety makes it easier to eat enough. Still, build most meals around nutritious whole foods, and keep fast food and sweets as occasional extras rather than the base of your diet.

  1. Eat more snacks

Since fasting only allows you to eat during a restricted time window, people often stick to eating 2-3 meals because they don't feel hungry in-between.

If you need a large calorie intake, three meals may not be enough. Add protein-rich snacks within your eating window, such as Greek yogurt, milk, or a protein shake.

Takeaway message

In adults who strength train and eat enough protein and calories, time-restricted eating does not appear to cause meaningful muscle loss. It can make a large calorie surplus harder to reach.

For children and teens, fasting is not recommended without medical supervision, since they need steady energy and nutrients to grow.

Hopefully, this article managed to address the common misconception around fasting and muscle hypertrophy.

If you have any questions, our comment section is open for discussion.

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