Can my sim get fat while having High Metabolism ?

Hello!
Does anyone know, is it possible to get my sim fat, while he's having the High Metabolism trait?
I've been feeding him nothing but cakes for a week and his body size didnt change, only the muscle definition faded. Now i removed the trait via console, but its been 3 days and his size still didnt change, so im not sure how it works at this point.