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What is Anabolic Fasting and Can It Turn Your Body Into a Fat-Burning Machine?


The anabolic diet was first developed by Mauro DiPasquale, a former world champion powerlifter and assistant professor at the University of Toronto. It later became popularized in the fitness industry as it promised to turn your body into a fat-burning machine. The name “anabolic diet” comes from DiPasquale’s belief that a certain method of carbohydrate cycling can mimic the effects that anabolic steroids have on the body. Anabolic fasting came along when CrossFit trainer Cory Gregory combined DiPasquale’s anabolic diet with principles of intermittent fasting to create a new protocol meant to build lean muscle while burning fat.

Read on to see what this diet entails and how it holds up from a physiological and safety standpoint.

What is Anabolic Fasting?

In the body, anabolism refers to growth and building, whereas catabolism refers to the process of breaking food down and using it as energy by the body.

Based on these terms, the proposed goal of anabolic fasting is to build up muscle through a reduced consumption of carbohydrates. The concept of fasting for muscle growth may seem counterintuitive, but it involves providing the right amount of nutrients to support anabolism while at the same time minimizing the body’s fat stores.

In its essence, anabolic fasting is an eating protocol that cycles between fat-burning and muscle-building stages through two main processes:


Carb-cycling involves restricting carbs on some days, and consuming a large number of carbs to replenish glycogen stores on other days. Here’s a general idea of what that may look like:

  • 5:2 cycle: For five days straight, the goal is to consume just about no carbs (as little as 25 grams or less.) During this low-carb phase, the goal is to eat a ketogenic diet, with most daily calories coming from healthy fat (65%) and protein (35%). For the following two days, flip things around: most of your daily calories should come from carb sources. High-carb days call for 60% of calories from carbs, and only 15% from protein and 25% from healthy fats.
  • Usually, people will choose to have their low-carb days Monday through Friday and then go high-carb on the weekend.

It’s important to point out that before starting on a 5:2 cycle, the protocol is to spend 12 days consuming no carbs in your diet in order to get your body properly adjusted to using fat, not carbs, as its primary energy source. After that, there are two high-carb days to replenish your glycogen stores and then you jump into the 5:2 weekly cycle.


On top of cycling between high-carb and low-carb days, this diet also involves a fasting protocol. That means you have a relatively small window each day, where you consume all your calories, and then the rest of the day you only drink water.

  • With the intermittent fasting aspect of the diet, most follow a 16:8 pattern where they consume all their daily calories within an 8-hour window.

What You Eat / What You Don’t Eat

  • Aside from carb restriction on certain days, there aren’t any foods you are not allowed to eat.
  • In general, anabolic fasting calls for healthy sources of protein, such as lean meats, fish and eggs, and healthy sources of fat, such as olive oil, dairy, nuts and avocado.

For the high-carb portion of the protocol, you should eat minimally processed, whole food sources such as vegetables, fruits, brown rice, whole grain pasta and oatmeal.

Pros and Cons

Carb restriction coupled with intermittent calorie reductions has been shown to improve insulin sensitivity and reduce body fat. Still, there are few scientific studies that evaluate the efficacy of carb-cycling on muscle growth and anabolism. There aren’t any studies that prove this method can burn fat while bulking you up; the evidence is mostly anecdotal from bodybuilders who follow Cory Gregory’s diet plans.

With any diet that calls for restricting an entire macronutrient group, there are risks of nutrient deficiencies. During the carb-restriction period, intake of valuable micronutrients such as thiamine, folate, iron, iodine and magnesium may be reduced, which can lead to serious deficiencies and poor health outcomes over time.

Intermittent fasting also requires you to eat fewer calories and less frequently than you normally would. If your goal is to build muscle, you may have trouble getting enough calories and protein to power you through a workout and adequately cover your energy needs.

The Bottom Line: Anabolic Fasting

Anabolic fasting combines two fairly difficult-to-follow eating patterns: carb-restriction and intermittent fasting. Whether you’re a bodybuilder, powerlifter, competitive athlete, casual gym-goer or anything in between, it is important to assess whether or not you can follow these protocols without compromising your health or wellness goals.

For example, for someone who needs fuel before a workout, the IF portion of anabolic fasting may result in some morning workouts while fasting that cause negative side effects (dizziness, fatigue, weakness and headaches.) The carb-restriction period may also come with symptoms similar to those that some people experience while starting the ketogenic diet, such as brain fog, nausea, headaches, fatigue and irritability.

All-in-all, the best diet for muscle gain is one that promotes muscle repair and replenishes the glycogen stores lost during intense exercise. You can do this by eating consistently and incorporating all macronutrients—proteins, fats and carbohydrates—into your diet. If you plan on giving anabolic fasting a try, make sure to focus on minimizing bad carbs such as pasta and cereals and focusing on whole grains, veggies, fruit and legumes to meet your body’s carbohydrate needs during the carb-loading period.

(Image: Shutterstock)

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