Gaining

Why am i gaining only in my lower half?

Checked your profile for stats, and at 5’10” and 157 lbs I’m pretty sure the reason is that you haven’t gained enough yet to start storing it in those places. You’re still at a normal BMI, and talking about traits of overweight men. Have a little patience. With that build, you may have a gut before you’re officially overweight, but you’re not there yet.
4 years