I had some dude in the gym asking me a question like this every time he saw me at the gym a while back when I was still kickboxing. Guy must have been about 6' and 250 lb. Not a 'good' 250 lb. either, if you get my drift. Never saw him even break a sweat.
I told him, diet - cardio - strength training for about the first dozen times. Finally, after enough pestering, I just said, "Dude, you will lose weight when you finally realize that the four food groups are NOT dough, tomato sauce, cheese and pepperoni."
He pretty much left me alone after that...