I think it has something to do with an old study which says that overweight and obese people with more fat distributed towards their thighs and ass instead of their belly having better health outcomes. However, this only applies when comparing between people of relatively equal body fat percentages and is more of a topic of body fat distribution than quantity. So, a femayo with cottage cheese thighs will definitely be more unhealthy than the normal weight chick with a thigh gap.