Muscle guy 

Any person who works out, who can’t grow or gain size but walks around like they’re the biggest person ever.

There a lot of muscle guys in the gym today

Muscle guy by @smoochsmacker December 20, 2018

Musclegut

When a person is fat or has a bit of a belly but is actually significantly strong.

Person 1:Man that kid is big.

Person 2: Yeah but he's got that 'musclegut'

Musclegut by CdB127 January 10, 2012