Blaž Hrastnik - Musclemania Pro says, "The difference in strength is immense regarding the percentage of body fat you have. You can have the same caloric intake when you're around 3-5% BF as you would when having 10-15% BF. However, the strength between these two scenarios varies up to 30%. Fat around your muscles helps keeping your joints warm and stable. It also acts as a source of energy during heavy lifts. Anyone who has been around 4% BF knows what i am talking about..also it's no wonder strongmen are covered in fat."