Can you burn fat and build muscle at the same time?

When starting, most beginners want two things at once: burn fat and build muscle. Many commercial products focus on this: fat leaves problem areas, and muscles grow where there is little volume. It is a very convenient replacement of fat for muscle. But what does the science say? Who can lose fat and build muscle at the same time?

Muscle growth is the formation of a new protein in the body. This is the assembly of new molecules from the building blocks – amino acids that we get with food. The process takes place in ribosomes – special matrices inside each cell. They stick together amino acids into new molecules in a certain sequence. This sequence is taken from DNA – she gives the “template” according to which everything will be assembled.

The formation of a new protein in the body occurs continuously throughout the day. But it also falls apart during the day. For any person, this protein cycle occurs daily – the old and spent own – disintegrates, and the new in its place – is formed. The ratio of protein synthesis and its breakdown gives three options for the development of events ( 1 ):

1. More protein is synthesized than broken down – muscles grow.
2. More protein is broken down than synthesized – muscles shrink.
3. Protein synthesis equals its breakdown – the muscles remain in the same quantity.

The effect of training on muscle growth

Strength training can lead to muscle growth if enough amino acids are supplied through meals throughout the day ( 3 ). And theoretically, these two stimuli of muscle growth – enough protein in food and loading the muscles – can also be on a calorie deficit.

The effect of calories on muscle growth

A positive energy balance, a calorie surplus, is also a muscle growth stimulus when it comes along with strength training. And this option leads to the most tangible results because, with nutrition, the body receives sufficient energy and building material.

When it’s possible?

And although the body is bad at doing two opposite things at the same time, there are several situations where fat loss and muscle growth occur at the same time.

Beginners

When people first start training, their strength grows rapidly, and the muscles easily respond to the load. A beginner’s body easily reacts to even the slightest stimuli, unlike those who have been practicing regularly for a long time and are forced to use all possible and impossible approaches and tricks to progress.

Therefore, at first, a beginner can lose weight and slightly increase muscle at the same time. Strength training and enough protein can sometimes (but not everyone) be enough, although the effect is very short-lived – a few weeks.

One of the consequences of being overweight is the insensitivity of body cells to insulin. When a person begins to train regularly with weights, the sensitivity of muscle cells to insulin improves, and they begin to take glucose better because this is the main fuel for work. Fat cells, crowded before, get an incentive to get rid of completely “extra” energy. It looks like a process of turning fat into muscle when a person practically does not change in weight but becomes slimmer and more prominent.

The leaner a person becomes, the longer he trains, and the more this effect fades – the fat cells are no longer so crowded to give away fat easily, and the muscles are not so untrained to respond with growth to any load.

Workout after break

People who used to exercise regularly and were in good shape but had to take a long break from training often see themselves getting back in shape much faster than those who train from scratch ( 4 ). They seem to replace fat with muscle magically.

The muscles remember the previous physical preparation, even when they atrophy. Simplified, the mechanism looks like this:

Every cell in the body has a nucleus inside it, which contains DNA with genetic information with which the cell can be copied. Muscle cells are very large and long, they are thousands of times larger than other cells in the body, and to maintain their volume (and even more so to increase), it is not enough for them to have one nucleus, which carries the genetic information for collecting new proteins.

Research has shown that under the influence of strength training, muscle cells receive new nuclei to make the process faster and more efficient – by fusing with dormant, inactive cells called satellite or stem cells located between muscle fibers.

These cells donate their nuclei to the muscles. When muscles atrophy, additional nuclei are not lost anywhere and remain in the cell ( 5, 6 ). Thus, when you return to training, the extra nuclei are already there and can quickly begin the synthesis of a new protein for muscle growth. That is why the muscles grow very quickly for those who return to training after a break – they do not grow so much as they return to their previous shape.

Chemists

Anabolic steroids and other drugs allow a person to go beyond normal physiology and do things that mere mortals can only dream of: increase muscle without fat (or even lose it), burn fat without losing muscle, maintain a minimum percentage of fat, and a lot of muscle all year round.

Fat burning and muscle gain for everyone else

Any person with training experience knows that you cannot burn fat and build muscle simultaneously. The main problem is that the body of a person who is at least somewhat trained could be better able to do these things simultaneously.

Over time, the muscles cease to respond easily to any load, and all incentives need to be increased – train more, come up with tricky training schemes, eat more protein, and eat more.

Losing weight also ceases to be as easy as at the beginning: there is already little fat in the body, and it is in no hurry to part with the “last” reserves.

And even greater difficulties arise when you want to do both simultaneously. This makes a person stagnate: calories are too high for fat loss and too low for muscle growth.

Fat burning and muscle gain require different and mutually exclusive conditions: different hormonal levels, nutrition, and physiological processes.

Moreover, those conditions that make it possible to increase muscle are why fat is also gained. These are anabolic processes – the conversion of energy received with food into muscle and fat mass.

And the reverse situation: the conditions necessary for burning fat are why the muscles “burn” too. These are catabolic processes when body mass is broken down with energy formation. Trying to do these two things simultaneously is like trying to turn a car in both directions simultaneously.

How to be?

So, unless you’re a high-fat beginner, a former exerciser, or a jock chemist, you probably won’t be able to build muscle and lose weight simultaneously unless you’re genetically gifted. Therefore, there are two options.

The Classic Approach: Muscle Building and Cutting Cycles

The most effective option is to choose one goal and work on it. That is why professional bodybuilders use cycles of muscle gain and fat burning and drying. They can vary in duration from a few weeks to several months. Separated by phases, these processes are much more efficient.

Cyclic diets

Some methods for experienced bodybuilders offer conditionally simultaneous muscle growth and fat burning when a person is in the fat-burning phase for part of the week and the mass-gaining phase. It is quite difficult and painful to implement the nutrition and training scheme, which requires complete immersion and strict adherence to all the rules. Therefore, they are unlikely to suit the majority. Lyle McDonald’s famous UD 2.0 diet is based on this.