Can You Build Muscle in a Calorie Deficit? Yes, But There’s a Catch

Is it possible to build muscle in a calorie deficit? If so, what’s the best way to go about doing so? Here’s everything you need to know.

Long story short, it is possible to gain muscle in a calorie deficit. Not everyone can do it, and not everyone can do it to the same extent.

But it can be done.

Today, I want to take a closer look at the results from one of the many studies showing that losing body fat and building muscle can happen simultaneously.

Then I’ll talk about how it happened, as well as explaining the best way to go about gaining muscle in a deficit.

Let’s jump right in.

What Is a Calorie Deficit?

You’re said to be in a calorie deficit when you’re burning off more energy than you get from your diet.

When you’re in a calorie deficit, there’s less energy coming from the food you eat than your body needs to move, pump blood around your body and all the other stuff involved in keeping you alive.

For example, if your daily energy expenditure is 3000 calories per day, but you’re only getting 2500 calories from your diet, your total calorie deficit is 500 calories.

Because there’s now a mismatch between the amount of fuel your body needs and the amount it gets from food, it starts looking for something to plug the gap.

In most cases, that alternative will be the large depot of chemical energy stored in your body known as fat.

Some say that it’s impossible to gain muscle in a calorie deficit, mainly on the basis that building muscle is an energy intensive process requiring a calorie surplus.

In truth, a calorie surplus isn’t necessary in order to gain muscle. That’s because your body can use the energy supplied by body fat to power muscle growth.

How Your Calorie Intake Affects the Amount of Muscle You Build

Research shows that muscle hypertrophy tends to happen a lot more slowly when you’re in a deficit compared to a surplus [6].

That is, eating fewer calories to the extent that you’re in a deficit makes the process of building muscle a lot slower compared to being in a calorie surplus.

That’s because one of the things that slows muscle protein synthesis – the key driving force behind muscle growth – is a restriction in the availability of energy.

Were you satisfied with your rate of muscle growth when you were in a caloric surplus?

Probably not.

You’ll be even less satisfied when you’re in a caloric deficit, because the gains will come a lot more slowly.

In an ideal world, you’d like your body weight to stay the same, with every pound of fat mass lost replaced with a pound of lean muscle mass (AKA body recomposition).

This is highly likely not going to happen.

With very few exceptions, you won’t build muscle at anything like the same speed at which you lose fat. Which means that for most people, fat loss is going to mean weight loss.

Building Muscle in a Calorie Deficit: The Research

When I heard about a study supposedly showing 16 pounds of fat lost and 10 pounds of muscle gained — all at the same time — my BS detector started working overtime.

But when I looked at the research myself, there was no mistake. A group of eight men had lost 16.3 pounds of fat and gained 9.5 pounds of lean mass in just 14 weeks.

Is it really possible to build so much muscle while you’re in a calorie deficit?

The results I’m talking about come from a United States Sports Academy study looking at the effects of strength training and aerobic exercise on body composition in a group of overweight (27% body fat) men [1].

The men were assigned to one of two groups and trained three days per week for 14 weeks.

An endurance-only group performed both cycling and walking (30 minutes each at 60-70% heart rate reserve for a total of 60 minutes).

A cross-training group performed both cardiovascular and resistance exercise (8 exercises, 4 sets per exercise, 8-12 reps per set, 60 seconds of rest between sets) in a single workout.

The strength training program involved a mix of both isolation and compound exercises. Here’s what it looked like:

• Bench Press
• Lat Pulldown
• Military Press
• Barbell Curl
• Triceps Extension
• Leg Press
• Leg Curl
• Calf Raise

After 14 weeks, the group combining cardiovascular with resistance exercise were able to lose fat 16.3 pounds (7.4 kilograms) of fat while simultaneously gaining 9.5 pounds (4.3 kilograms) of lean body mass, which serves as a reasonable proxy for muscle mass.

That’s pretty impressive.

Truth is, losing 16 pounds of fat and gaining almost 10 pounds of muscle in 14 weeks is a result that most people would be very happy with.

Unfortunately, this isn’t a realistic goal for most people, and here’s why:

Firstly, the men taking part in the study were beginners, who tend to make rapid gains in muscle mass when they start training with weights.

They were also overweight, bordering on obese, with a lot of fat to lose [2]. Take someone who is untrained AND extremely overweight (which these men were) and they’ll often drop relatively large amounts of fat while gaining muscle at the same time.

Why do overweight beginners have such an easy time gaining muscle while losing fat?

People who are very overweight are usually insulin resistant to some degree. Insulin resistance tends to develop as you gain fat.

It appears to represent an attempt by your body to stop you gaining more, or to help you lose fat once the excess calories are removed from your diet.

Insulin is primarily a storage hormone. It helps to drive nutrients, such as glucose, from your blood into the cells of your body. High levels of insulin also inhibit the rate at which stored fat is mobilized (i.e. broken down and prepared to be burned off).

But when fat cells are insulin resistant, insulin doesn’t have the same effect. Which means that even in the presence of high insulin levels, fat can still be mobilized for fuel. The overall effect is as though fat cells are “full up” and resisting further fat storage.

When an overweight beginner starts exercising and dieting, nutrients are diverted away from fat cells (which are still insulin resistant) and towards muscle, which has become more insulin sensitive as a result of the training. Because there’s less glucose available, muscle cells will burn more fat.

Second, the researchers used underwater weighing to measure changes in body composition.

Although underwater weighing is still considered by many as the “gold standard” when it comes to estimating body composition, there’s still a surprisingly large margin of error, which can skew the results.

Researchers have compared underwater weighing with something called the 4-compartment (4C) model for assessing body fat change in individuals [3].

The 4C model is an expensive method of measuring body composition that divides the body into four components (mineral, water, fat, and protein) and measures each one independently.

Short of killing someone, stripping off their fat and weighing it, the 4C model is currently the best method available to predict body composition.

When underwater weighing has been compared to the 4C model, the size of the error is around 5-6% [6].

Which means that if underwater weighing puts you at 15%, your true body fat could be as low as 10% or as high as 20%. That’s a large range.

In other words, underwater weighing could tell you that you lost a relatively small amount of body fat, when the true amount lost was actually much higher.

On the flip side, underwater weighing could tell you that you lost a relatively large amount of body fat, when the true amount lost was a lot smaller.

Of course, this doesn’t mean that we should ignore the results of this study. But the accuracy of body fat testing is something to keep in mind when you see results that seem a little too good to be true.

How to Tell if You’re Gaining Muscle While Losing Fat

How can you tell if you’re losing fat while gaining muscle at the same time?

Stepping on the bathroom scales, the way that most people measure progress, gives you a limited picture about how your body composition is changing.

If you lose 10 pounds of fat while gaining 5 pounds of muscle, your weight will change by just 5 pounds. But your body composition has changed by 15 pounds.

Most tools available for tracking changes in body composition, such as DEXA or body fat scales, have a large margin of error. None can be relied on to give you an accurate assessment of your progress.

Instead, I suggest keeping track of your waist size, your weight on the scales, and your performance in the gym. 

And by performance in the gym, I’m talking about the amount of weight you can lift for a given number of reps, or the number of reps you’re able to do with a given amount of weight.

If your weight on the scales is going down, your waist size is shrinking, but your numbers in the gym are going up, those are all positive signs that you’re on the right track and what you’re doing is working.

How to Build Muscle in a Calorie Deficit

If you want to build muscle in a calorie deficit, what’s the best way to go about it?

First, make sure that you do some form of resistance training at least twice a week. Three times a week will be better. And, if you’ve got the time, four workouts a week is better than three.

That’s not to say you can’t do more. In fact, there’s no good reason why you can’t lift weights 5-6 times a week, just as long as your workout program is set up properly.

However, for most people wanting to gain muscle while losing fat, four days of weight training a week is plenty.

Although there are many effective training programs out there, a 4-day upper/lower split, where you work the upper and lower body muscle groups on separate days, is one of my favourites.

You’ll find a complete 4-day upper/lower split here.

As for cardio, it’s useful in certain circumstances, but not essential. As long as your diet is set up properly, losing fat doesn’t have to involve any cardio at all.

Nutrition for Building Muscle and Burning Fat

On the nutrition side of things, there are two key things to focus on:

1. Make sure the calorie deficit isn’t too large
2. Eat a high-protein diet

If the number of calories you eat each day is too low, you’ll struggle to hold on to the muscle you have right now, let alone gain any more.

Setting your daily caloric intake will depend on a number of factors, one of the main ones being the amount of fat you have to lose in the first place.

If you’ve got a large amount of fat to lose, you can still build muscle while maintaining a relatively large energy deficit. But as you get leaner, the more extreme the deficit, the higher the risk of muscle loss.

As a general rule, aim for a calorie deficit somewhere between 15-20% below your maintenance calorie intake. And by maintenance calorie intake, I’m talking about the number of calories you need each day to maintain your weight.

What about protein intake? How much protein should you eat to gain muscle while losing fat?

Aim for roughly 0.7 grams of protein per pound of body weight per day, or around 1.6 grams per kilogram [4, 5].

Without enough protein, you’ll find it extremely difficult to retain muscle mass, let alone gain any.

In summary, some people can and do build a decent amount of muscle while they’re in a calorie deficit.

But it’s a phenomenon that’s generally limited to people who are very overweight and have never lifted weights before, or those who are returning to exercise after a layoff, where muscle memory comes into play.

Once you’ve move past the “overweight beginner” stage, building a significant amount of muscle while losing fat is a goal that becomes progressively more difficult.

Frequently Asked Questions

Is bulking necessary or can you build muscle well enough in a deficit?

Overweight beginners can expect to build a decent amount of muscle in a deficit. But more advanced lifters are better off focusing on fat loss or muscle growth, using a traditional bulk or cut approach.

Can I lose muscle mass in a calorie deficit?

Yes, you can lose muscle in a calorie deficit. Cutting calories too much, combined with a low-protein diet and little or no resistance training can increase the rate of muscle protein breakdown, which will lead to muscle being lost.