No, fat does not turn into muscle and vice versa. It is a common question we hear quite often. Clients say that the extra fat they carry is “turning into muscle.” The truth is muscle and fat are two different organs with different functions.

Fat is basically a storage system for energy. When we overconsume calories, the extra energy is stored in our fat cells increasing our body fat percentage. Muscle is an organ that gives us the ability to move. Since we are moving constantly, we are expending energy at a constant rate. Muscles use the energy provided by our fat cells to support our everyday functions.

Why has this question become so common? When people start working out, muscle mass increases and fat percentage drops slightly. Remember that with a proper diet, our body fat percentage will drop quicker than with exercise alone. In other words, our body composition changes. The opposite is true as well. When someone stops working out, their muscles start to atrophy (shrink in size), fat cells hypertrophy (grows in size), and our fat cells increase in number. This perfect storm of negative side effects makes it seem like our muscles turned into fat.

Sean Willitts is an ACE certified personal trainer. He graduated from Kutztown University in 2015 with a bachelor’s in sports management and a minor in fitness. Including training at Body Elite, he is also a record holding powerlifter. He uses his practical experience and knowledge to help his clients achieve their strength and fitness goals.

Source: https://www.elitefts.com/education/does-muscle-turn-into-fat/