system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some men gain weight all over while others gain it only on their belly?

I've always had a little extra weight on my belly. In the last 3 years, I've gained 20lbs and it has gone entirely to my belly with no noticeable gain on my limbs, neck or face. My extra weight is far more noticeable than it should be as it's all in one place. Why do I gain like this?
gpt
It's genetic. Your genes determine where your body places fat. There's other factors that get involved, mainly age and hormone levels, but beyond that, some folks just get fat all over, others just get fat in specific areas.