Yeah, by any definition I am a gym rat.  I've known precisely ONE guy who is obese purely due to muscle mass and as you might guess, he looks like it.  Yet half the fatties on the internet are apparently just obese due to muscle. As for lifting "more", the fat limits your range of motion and makes it seem like you are stronger than you are.  Fat guy at my gym curls 100 pound dumbbells less than 6 inches, no joke.  It's not hard to lift a lot of weight if you're only going a few inches and using your entire body.