Yep, or the other way round, people with this or that problem in digesting food (or however food related symptoms even if not a proper allergy or medical condit

Yep, or the other way round, people with this or that problem in digesting food (or however food related symptoms even if not a proper allergy or medical condition) tend instinctively to eat less, hence they are thinner, while "healthy" people that have no adverse effect from eating anything tend to eat a bit more and are thus fatter.