Basically any word or short phrase I can think of to mean “a lot of muscle” also implies skinny or almost no fat. Fit, or lithe bring to mind more a track athlete’s body, and buff, ripped, jacked, muscular, ect. generally are though of more like a body builder. The closest thing I can think of is dad-bod but thats obviously still pretty far off as well as being male-specific. Is there even an English word for this?
“stout” is the first that comes to mind and isn’t immediately discarded. But because those other forms are so easy to call to mind I’d rather describe the power-lifter as they differ from those norms.
“He was no body-builder. Powerful, yes, but he had traded aesthetics for even more strength. Muscles built upon muscles like layers of a brick house, and nearly as solid.”