"Fat does not make you fat. Eating too many calories makes you fat. It just so happens that a gram of fat has more calories in it than a gram of protein or carbs. However, the only thing that makes a person gain fat is when that person is eating more calories than their maintenance level, and then not burning them off through working out. Whether these excess calories in your diet plan are coming from protein, carbs or fat makes little difference."

http://www.intense-workout.com/diet.html