Stopped Exercising — Your Muscles Won’t Turn To Fat But Your Body Might

​If you weigh the same and your muscles are shrinking, then you are adding fat

Photo by Holger Link on Unsplash

Since the lockdown began, I have had to stop doing my more intense strength exercises at the gym — I used to go three times weekly.

Like you, I’ve read that our muscles “turn to fat” when we stop exercising. That’s a scary thought, especially after 20 years of progressively building my muscular strength and endurance.
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There’s good news and bad news. The good news is that our muscles don’t turn to fat — that’s not even remotely true. The bad news is that our bodies will accumulate more fat if we continue to eat the same amount as we did with more muscle.

You don’t lose the muscle, you lose the volume of muscle

What actually happens when we stop training and our muscles get smaller, is not really losing muscle. But the muscle fibres are getting smaller — shrinking. We still have the same number of fibres, which is how we can rebuild later.

This is a very clever process of adaptation by our body. Muscles take energy to feed them — hence why muscles are good for burning calories. When we stop using specific muscles our body interprets this as a signal that those muscles are no longer needed for our survival. It shrinks them in order to not waste energy, Makes sense, right?

The shrinking fibres also lose (1) mitochondria, which are the energy powerhouses of our muscles, and (2) they lose blood capillaries which have grown in response to training in order to feed oxygen to hungry, active muscles. As these bad boys atrophy, we lose our conditioning and strength.

Here’s an interesting factoid: as we build muscle size and strength new nuclei develop in our muscle fibres. Researchers found (2013) that when we “detrain”, or rest for extended periods, these new nuclei remain even though the fibre size shrinks. These extra nuclei are thought to help in accelerating the recovery of our strength when we get active again.

How long before my muscles start shrinking?