Can You Lose Fat and Build Muscle at the Same Time?

Is it possible to lose fat and gain muscle at the same time? This is a topic that generates a lot of debate in the fitness community.

A generally held belief is that you need a calorie deficit to burn fat and a calorie surplus to gain muscle. But then we also have a few studies showing that an increase in muscle mass can occur along side fat loss, as long as you’re eating enough protein and combining diet with resistance training. So what should we believe?

Like many health subjects, the biggest reason for this confusion is a lack of research. Most diet studies show that when a person goes on a diet they generally lose both fat and muscle. Under some conditions, which I’ll talk about in this post, it’s possible for you to gain muscle while losing body fat. The process of doing both at the same time can be slow and inefficient–but in many ways getting in shape this way is likely to give you the best long-term results.

Gaining Muscle and Losing Fat as Goals

The idea that you can only focus on building muscle or losing fat is largely driven by the bodybuilding community. Competitive bodybuilders spend part of the year in a “bulking phase”. They eat a surplus of calories (more calories than the body needs to stay at the same weight) to gain as much muscle as they physically can, knowing they will also gain fat along the way.

Then they go through a “cutting phase” where they cut calories and try to shed body fat, hoping to keep the muscle they built. The cutting phase usually involves a strict diet high in protein with continued resistance training to hopefully preserve muscle mass.

Bodybuilders set the timing of these phases based on when they have a competition or photoshoot that they need to look their best for.

Bulking and cutting phases don’t work well for most people for several reasons:

  • They require daily monitoring of calorie intake over many months
  • Over-eating and under-eating cycles are difficult to adhere to long-term
  • The cutting phase requires a highly restrictive diet

Bodybuilders also diet this way so that they look their most fit only a certain times of the year. “Bulking up” means you’re going to look at least slightly out of shape or chubby for part of the year and I think most people would rather look good year round.

Over-eating to purposely gain muscle can end up adding a lot of fat that may be difficult to shed.

By taking a more consistent approach your results will come slower, but they’re more likely to last.

How Does the Body Build Muscle and Burn Fat at the Same Time?

Dieting to lose fat means taking in less calories than your body is expending during the day. Even though your calorie intake is less than what your body is expending, your body is not in a calorie deficit. It uses fat stores to generate energy and make up for whatever is not being supplied in the form of food.

So even in a calorie deficit your body has the energy and nutrients it needs to build new muscle. The body may not choose to dedicate a lot of resources to building muscle tissue, but that’s where lifting weights and getting enough protein factor in.

Catabolism vs. Anabolism

The body’s metabolism can be broken down into two parts: catabolism and anabolism.

  • Anabolic activity builds things and requires energy
  • Catabolic activity breaks things down and give off energy

Gaining muscle is an anabolic activity. Losing fat is a catabolic one. Anabolism and catabolism are ongoing processes–not static phases. Both occur together and are regulated by hormones circulating through the body. The breaking down of fat to create energy is a separate process from adding protein to muscle tissue.

One study that highlights this ability to lose fat and build muscle simultaneously came out of the United States Sports Academy. A group of men lost 16 pounds of fat and gained 10 pounds of muscle over a 14 week period using diet and resistance training.

What should be mentioned about the subjects in that study is that they were overweight and were not exercising before the study started.

If a person has a lot of weight to lose, it’s going to be a lot easier for them to see rapid fat loss because people who are overweight are generally insulin resistant. Basically, their bodies are more willing to give up stored fat to be used as energy than someone who is leaner.

A similar thing happens with people who begin weight lifting, or return to training after a layoff. Someone just starting out on a resistance training program has the potential to gain muscle at a faster rate than a more advanced weightlifter.

For someone starting off with a high body fat percentage I think the focus should be on reducing calories.

Good eating habits are by far the most important aspect of body composition. As long as you are doing strength training workouts along with a reduced calorie diet with an adequate amount of protein, there is the potential to gain a good amount of muscle mass as you lose weight.

The leaner a person is, and the more trained their muscles are, the more difficulty they will have gaining muscle and losing fat at the same time.

Someone who is leaner or has been training with weights for a while has a more difficult choice to make. They can either:

  • Make fat loss the priority
  • Make gaining muscle the priory
  • Attempt body recomposition (simultaneous fat loss and muscle gain)

A lot of fitness professionals will recommend setting either fat loss or muscle gain as your goal. Focusing on one or the other allows the body to efficiently work toward whichever direction you choose to go. Choosing only one goal works well for people who know they have the ability to adhere to a set diet.

You can choose to focus on reducing body fat percentage with the realization that you probably won’t see tremendous changes in muscle size or strength.

At least one study has shown that for trained athletes lean body mass can be increased during a weight loss period as long as the weight loss is not drastic. This study out of the Norwegian School or Sport Sciences showed that athletes gained muscle (and strength) while dieting to lose 0.7% of their body weight each week. Athletes in a more rapid weight loss group (1.4% of their body weight per week) only preserved their existing lean body mass. Both groups did strength training workouts four times a week.

The key here seems to be focusing on losing weight at a very slow rate. This is done by only slightly reducing your calorie intake below your maintenance level, or the amount of calories needed to stay at your current weight.

You can choose to increase calories above your maintenance level to focus on gaining muscle with the realization that you might also add some fat if your calorie intake is too high.

The goal here is obviously to put on muscle without adding fat. The problem with this approach is that people will often end up over-eating and gaining a lot of fat.

A big mistake people make when trying to gain muscle is that they’ll start eating everything in sight without thinking about the quality of the food they’re eating. The same foods you would eat if you were trying to lose weight should be the foods you eat when you’re trying to gain muscle.

You can choose a body recomposition diet which typically involves switching back and forth between high calorie days and low calorie days.

An example of this type of diet would be eating above your maintenance level of calories on days that you train, and eating less calories on your off days. There are also carbohydrate cycling versions of this dieting strategy which work well. These diets can be effective for someone who is very regimented with their food intake and knows they have the ability to control calories.

A last option, and the one I prefer, is to simply focus on eating healthy and working out instead of worrying about how muscle gain or fat loss.

There is a lot of research showing that people who are too rigid in their approach to dieting end up being less successful in the long run. You can instinctively eat the right amount of food to allow you to get lean and gain muscle simultaneously.

I think to some degree people have become convinced they can no longer trust themselves to know when they are hungry. By concentrating on making healthier food choices and working out your body will naturally regulate cycles of building muscle tissue and burning fat.

This approach involves:

  • paying attention to the energy demands of your body
  • making sure you have plenty of access to healthy food choices
  • limiting the availability of unhealthy foods
  • eating when you feel hungry

The changes in body composition won’t be as immediate as someone who goes on a 12 month bulk to gain muscle mass or crash diet to lose weight, but over a long enough time frame I’m willing to bet the results will be the same if not better.


The main point of this post was to explain and offer some evidence that you can lose fat and build muscle at the same time. Don’t be deterred into thinking you can only choose one or the other–especially if you are just starting to exercise. There are many different approaches you can use to reach your fitness goals and only you can decide what is going to work best for you, both in the short and long-term.

Two websites I recommend to anyone looking for good, science-backed information about the different aspects of weight-loss and muscle building are Martin Berkhan’s Lean Gains and Lyle McDonald’s Body Recomposition.

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