Myth-busting: Can muscle turn into fat?

The health and fitness industry is full of false, misleading and sometimes dangerous information. In this series of blog posts I will tackle some of the misinformation and common questions found online. The first; Can muscle turn into fat ?

The short answer: No, Muscle does not turn into fat.

What is Muscle ?

Muscle tissue consists of long cells that contract when stimulated and produce motion. Muscle tissue attaches at either end to a fixed point and that by contracting moves or resists the movement of a body part.

What is Fat ?

Fat is a source of energy for the body. Food is broken down into glucose to be used by the body immediately. Excess glucose is then stored as glycogen. Excess glycogen is stored as fat. When the body needs energy this process is reversed, fat is broken down into fatty acids and glycerol for the production of energy.

The Process of loosing muscle and storing fat.

Muscles can atrophy. If you have atrophied muscles, you’ll see your muscle mass and strength decrease. Muscle atrophy happens due to malnutrition, age, genetics, a lack of physical activity or medical conditions. When muscle mass decreases due to lack of physical activity the human body requires less energy. If your diet remains the same, the energy that is no longer required by your now smaller muscles will be stored in fat cells for later use.

Can muscle turn into fat?

While muscle does not directly turn into fat, the loss of muscle can lead to the storage of bodyfat. It is important throughout your life including old age to maintain and build muscle.

Barclay, C.J. Energy demand and supply in human skeletal muscle. J Muscle Res Cell Motil 38, 143–155 (2017). https://doi.org/10.1007/s10974-017-9467-7