Do Black people have more muscle mass than any other races?

I got routine lab work done and my doctor said my lab results were excellent and he asked me if I was an athlete? I was shocked by the question because I'm actually 10 pounds overweight. I told him No. Is it because I am Black and I just have it naturally? I also noticed white women who are in the same age group as me look very fragile and their body looks like its sagging. Is it because I have more muscle mass that I still looked tone even though I'm 10 pounds overweight?