Lean mass increases until approximately age 25, then gradually declines by 8-10% per year between ages 25 and 75, followed by a significant decline after age 75.

“fat free Mass um you know Rises up so i. e lean mass kind of Rises pretty significantly from birth till about the age of 25 and then it slowly starts to go down by the way this is true for males and females males are on the right females are on the left so you'll notice that from age 25 to 75 there is indeed a gradual reduction of lean mass but then something happens at the age of 75 which is the falloff in lean mass becomes much more significant it's actually even more noticeable in men presumably because they're starting from a higher Baseline but this is clearly a curve that has three segments right birth to 25 where you're gaining gaining gaining 25 to 75 where you're slowly losing uh and by the way we know the numbers right we know that that's actually happening at 8 to 10% per year and then 75 and on where you fall off a cliff”