Maybe not pure bullshit, hear me out. I have no idea what study or survey they are citing. But if some athletic people have premature aging vs overweight people, I think sun exposure is a major uncontrolled factor in such a comparison. Athletic people tend to spend more time outdoor and in the sun. If they don't protect their skin, they could get UV damage to the skin. Over time, it will impact the collagen  production and reduce skin elasticity. If you control for unprotected sun exposure, I'm certain the thinner and athletic group would look younger than the overweight group.