Mens bodies do sag and we lose testosterone which makes it very hard to gain muscle.
Sagging examples on fit men:
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And these guys are elite athletes competing in the oap bodybuilding competition. They look great for their age and if we look this good after 65 then we are lucky, but lets not pretend that their skin has not sagged.
They will just have lost lots of weight so they have loose skin, like a woman whose had a kid. That isn't sagging caused by age. If a man doesn't gain and lose lots of weight that will never happen to him.
Studies show that men who don't get fat have no drop in testosterone, fat cells produce estrogen which cause breast growth, lower testosterone etc.