How Fast Do You Lose Muscle Mass?

There’s credence to the saying “Use it or lose it.”
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How fast you lose muscle mass varies from one person to the next. How old you are, how active you are and the body type you inherited from your parents can all be factors in how your body gains and loses muscles. Extreme diets can also affect the rate of your muscle loss. If you’re young and working out frequently, your muscle loss will be a matter of several weeks or even months away from your fitness routine. As you age past your 40s, the passing years will inevitably shrink your muscles.

Hypertrophy vs. Atrophy

Muscle growth, or hypertrophy, comes easier with strength training and growth spurts during your teenage years. The loss of muscle mass, or atrophy, can set in at any time in your life from illness, injury, inactivity and aging. When it comes to losing muscle mass, time is your enemy, whether you work out or not. In the words of former bodybuilder Arnold Schwarzenegger, “As we get older the muscle structure tends to atrophy at a faster and faster rate.”

Principles of Atrophy Rate

At any age, taking an extended break from your workout routine can cost you some of that hard-earned muscle you’ve trained to build. This is known as the use and disuse principle. Because you’re an individual with a distinct combination of physique, diet and workouts, the exact rate that disuse atrophies your muscles may differ from others.

Diet and Muscle Loss

To lose fat, you have to burn more calories than you consume, and many people exercise specifically to burn calories. However, extreme diet restrictions can tip this balance too far and your body starts to sacrifice muscle mass. If you don’t provide your body with its preferred fuels, your muscles will shrink. This kind of atrophy can even break down your muscles' ability to function.

Muscle Loss and Aging

Past the age of 35, your body gradually loses muscle mass. This form of atrophy is called sarcopenia. Loss of muscle mass due to aging can vary among individuals based on activity, diet and general health. In this sense, sarcopenia is highly individualized. Unlike loss of muscle mass for some young people, sarcopenia causes atrophy in everyone as they age into their 40s and beyond.


You should consult your doctor as well as exercise and nutrition professionals before changing your diet and fitness routine. This is especially true if you’re responding to adverse affects and planning to resume dieting or workouts after time away from your exercise and nutrition programs.

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