No, we don't. In the absence of some specific medical condition, the difference in weight between those genetically disposed to be fat and those disposed to be skinny is, on a similar diet, about 10 pounds. Not nearly enough to account for the 50 pounds you want to shed. genetics is just an excuse, not an explanation. Everybody who consumes more calories than they burn up puts on weight. That's the end of the story. And other posters have it right about beer. Alcohol completely screws up your metabolism and replaces your body fat as principal food source.

Eat less. Drink less beer. Don't expect a few hours exercise each week to keep you thin, because it is never going to happen.