I hadn't noticed a problem with my Sims getting embiggened if they weren't gymrats, in a long time, but I had to wonder, was that because all my Sims were gymrats? LOL
So glad you brought this up because body image problems in men are often missed because they don't look take the same form as in women. Bigorexia is a real problem and it's a threat to health that's harder to deal with because it's often invisible. After all, a guy who's swole and ripped, looks like he must be well-fed, but sometimes he's living on extreme diet shakes and pursuing keto goals that can do lasting harm to organs and hormonal systems. Add diuretics, steroids, or both (thankfully I never abused either) and you've got a recipe for disaster a few years down the road.
I was just pondering how one of my Sims3 sims had a body as unrealistic and unhealthy for real-life goals, as a skeletal female sim would be. It's not healthy or natural to see every single intercostal muscle standing out in stark relief. We are influenced by representations of ideals, so it's important to try to keep our represented ideals, achievable within the bounds of health. Sims doesn't do this, because we also play for enjoyment of eye-candy and perfect people in a perfect world. But it carries risk, to internalize and normalize those extreme, unobtainable ideals.