Does Muscle Turn to Fat?

I’ve had more than one person ask me this.  There’s a commonly held belief that you’ll turn into a tub of lard if you lift weights then stop.  Some even believe working out will make them fatter. 

So, does muscle turn to fat?  NO!

Fat and muscle are two completely different types of tissue with different functions.  Can one type of tissue turn into another?  Can hair turn into bone?  Can your fingernails turn into teeth? 

Next question: can a lean, muscular person turn into a fat person?  YES!  
Can a fat person turn into a lean, muscular person?  YES!

Body composition (bodyfat level, etc) is dynamic—it changes according to one’s exercise and diet.  

A muscular person could become fat by doing the following:

1. Stopping his/her weight training.  Given enough time, the muscle would shrink (a process called atrophy). 
2. Eating more calories than he/she uses—which would eventually be stored as bodyfat. 

This process wouldn’t happen overnight, but eventually, the muscles would shrink and one’s bodyfat level would rise (if he/she consumed more calories than he/she used).

Likewise, a fat person could become more lean and muscular by doing the reverse:

1. Train with weights, which increases muscle mass (muscle growth is a process called hypertrophy).  The increased muscle mass would cause his/her metabolism to be faster, burning more calories 24/7.
2.  Eat fewer calories than he/she uses, or eat only as many calories as he/she uses (a negative or neutral calorie balance). 

The end result would be a decrease in bodyfat level and an increase in muscle mass.

One final question:  is a muscular person more likely to turn into a fat person?  NO.

I’ve seen former bodybuilders who are now in terrible shape.  But I’ve also seen guys in their 60’s and 70’s who look incredible.  It depends on how they eat and train.

I’ve also seen guys who were beanpoles in high school but now fight the battle of the bulge.  They got used to eating whatever they wanted, and it eventually caught up with their waistlines. 

This is a highly simplified explanation, but I think you get the point. 

Summary:

1.  The more muscle you have, the more calories you burn 24/7.
2.  Body composition is dynamic.  I changes according to diet/exercise.
3.  Muscle does not turn to fat--don't let this irrational fear keep you out of the gym.