Waist size is usually smaller on men than trouser measurements, since we wear trousers at the hips not the waist. I'm quite muscular and 6% bodyfat, I wear 32" jeans/trousers but my waist is about 30". Although it's true if you have a LOT of muscle, the waist can thicken out to 38" or so, but I'm talking pro bodybuilder size.