No, you can't turn fat into muscle.

The most common goal I hear as a personal trainer is the desire to drop body fat and gain lean muscle.

I love it! A fit, trim, and lean body is a healthy body.

But many do not understand what happens within our bodies regarding fat loss and muscle growth as we begin to exercise and eat right.

Does fat turn into muscle as I get stronger and leaner? If I stop exercising, will my muscles turn into fat?

Short answer: No.

There is obviously a ton of science to explain it, but I'm going to try to be as straightforward as possible.

Muscle and fat are two entirely different structures within our bodies and they serve two completely different purposes. One simply cannot change into the other.

We all have muscles. As part of the musculoskeletal system, muscle tissue makes movement possible, along with tendons, ligaments, and joints. To what degree our muscles grow in size or how adept our central nervous system is at activating muscles for strength falls on our level of fitness and the kind of physical activities we perform.

Muscle growth occurs when you apply enough consistent force and tension to your muscle fibers that they respond by growing bigger. Muscle strength is the ability of your neuromuscular system — your brain, nerves, and muscles working together — to create the force required to move a heavy load.

As you lift weights and as your muscles grow and get bigger, the more calories you burn throughout the day, not just while you're exercising.

I love how this article from explains it: "Muscle is active tissue that burns calories around the clock even as you sleep, kind of like an engine running in neutral. When you move around, you burn more calories, just like a car will consume more gas the faster you go."

Fat, on the other hand, is an energy storage vehicle. The fat cells in your body take in triglycerides — the broken down form of fat that exists in most of our food and in our bodies — and store them as an energy reserve.

Carbohydrates are the body's preferred source of energy, but that energy is short-lived. Energy from carbohydrates typically sustains you for about 20 minutes of continuous activity or in short spurts of intense exercise, at which point your body dips into your fat reserves for a longer, more sustained energy flow.

Fat does nothing but sit there until you do enough physical activity that your body begins to burn it off for energy. And when you burn off fat and your fat cells begin to shrink, that "waste" leaves your body as a combination of carbon dioxide and liquid primarily in the form of sweat and urine.

But that fat does not turn into muscle.

The key to dropping body fat and gaining lean muscle is to first and foremost begin a weight-training regimen. By increasing your muscle mass, you'll kick your metabolism into a higher gear, causing your body to burn more calories throughout the entire day.

The crazy thing about this process is that as your muscles grow and your metabolism increases, in most cases, you'll be able to consume more calories per day and still see your body composition (i.e. body fat percentage) change positively.

Then, as you transition your workouts to include more exercise that elevates your heart rate and causes your body to dip into its fat reserves for energy — and this doesn't necessarily mean tons of steady state cardio — and also by watching what you eat and burning more calories than you are consuming, you'll drop body fat and weight.