Yeah, IIRC, there are three body types: ectomorph, endomorph and mesomorph.
One can't gain weight unless with extreme effort and supplements (ecto), one can't even touch food without gaining weight (endo) and one is a perfect balance of the two and represents what's known as 'ideal' (meso).
Most advertising uses mesomorph males (because they have an easier time building muscles and keeping weight off) and ectomorph females (because they're naturally leaner).
If an ectomorph or mesomorph gets overweight, there is a health problem. And their bodies aren't naturally prepared for it.
An endomorph being skinny is also a sign of a health problem, as their bodies are naturally prepared to store fat.
However, an endomorph can still become overweight if they're above their natural weight, just like an ectomorph can be at risk if they lose too much weight.
The problems stem mostly from the 'ideal' female image being close to an ectomorph natural, which isn't hard for a mesomorph to come close to with no health problems, but unnatural for an endomorph (and could cause problems).
The mesomorph 'ideal' for male puts less pressure on men, but ectomorphs still feel like they need to have muscles and or fat to appear acceptable and endomorphs still feel like they should be skinnier.
They just don't feel the same level of pressure that endomorph females do because the 'ideal' male is in the center of the spectrum instead of the far left.
Btw, the 'ideal' female image was closer to meso in the '50s, as Marilyn was pretty much the ideal of the time. But by the '90s, she could be seen as too heavy and referred to as 'plump' due to thinner models becoming the norm.
Btw 2, I'm ectomorph, myself. I can eat a Big Mac and fries right before bed and not gain a pound. But to actually gain weight, I would need to stick to a high protein/high carb diet of 3000+ calories a day and workout seven days a week.
After two weeks of this, I'd look more meso (and 'ideal'). But if I stopped working out and went back to a regular diet, I would be back to my natural thin shape within a week, and lose everything I worked so hard for.
On the plus side, after I hit 40 it's become a bit easier to keep some weight on, but no easier to keep muscle mass.