Today I’m going to talk about fat and muscle
Specifically, can your body convert muscle to fat, and vice versa? I’m going to tackle this in two halves, by answering two questions I often get asked.
The first is: “can I turn my fat into muscle?”
The second is: “if I stop working out, will my muscle turn to fat?”
The simple answer to both these questions is no.
But as with all things related to health and fitness, the complete answer is not really quite that simple.
To answer these questions, I need to briefly explain what muscles are and how they grow.
Muscles are built from protein. When you exercise your muscles, and if you provide your body with an adequate supply of protein[1], your muscle cells will grow larger and become stronger[2]. The number of blood vessels in your muscles also increases, improving performance and appearance[3].
Your body does not make muscles from fat.
It is however common to burn fat when working out, at least in small quantities[4]. In this way, you could argue that you’re converting fat to muscle, but really it’s more accurate to say you are losing fat and gaining muscle simultaneously.
So your body can’t convert fat into muscle, but with a bit of effort you can lose fat and gain muscle at the same time.
Losing fat and gaining muscle is easiest if you are new to working out and have some fat to lose. But it is possible for anyone to lose fat and gain muscle, by tackling one goal at a time. This is known as phasing, and works even for experienced bodybuilders and athletes[5][6]. For more on this topic, check out my vlog on setting your goals.
What about the opposite? Do muscles turn to fat when you stop working out?
When working out, muscle gains will be greatest if you are in a calorie surplus[7]. Working out requires a lot of calories – a single good workout can easily burn more than 500 calories. So if you have and maintain a lot of muscle, there’s a good chance you eat a lot of calories[8].
If you stop working out, two things happen. Firstly, your muscles will shrink and contract from lack of use. Secondly, you will burn fewer calories. If you keep eating the same as you did before, you will push yourself into a calorie surplus. If you do this, you will gain fat.
So your body won’t convert muscle to fat, but if you aren’t careful, it is very easy to lose muscle and gain fat at the same time.
