There is some truth to it. Your muscles do start to change in your 30s, says Alan Hayes, a muscle and exercise physiologist at Victoria University. "You have … peak muscle mass in mid-20s and certainly after that point, by about your mid-30s, they start to decline.

At what age does the body start deteriorating?

Some systems begin aging as early as age 30. Other aging processes are not common until much later in life. Although some changes always occur with aging, they occur at different rates and to different extents.

At what age do you stop growing and start dying?

Everyone generally ages at a similar rate until they reach their late twenties or mid-thirties. Unless you've inherited a rare genetic disorder or have been in an accident, at thirty you're probably basically healthy and able.