The first nutrient to cut back on when trying to lose weight is fat

True. On a gram-for-gram basis, cutting back on fatty foods reduces energy intake more than avoiding the equivalent amount of other foods. Fat contains 37 kilojoules per gram whereas carbohydrate and protein contain only 16 and 17 kilojoules respectively. This does not mean that carbohydrate and protein are not fattening. But if you cut back on say, 100 gram of sugar, you save 1600 kilojoules whereas if you remove 100 gram of fat from your diet, you save 3700 kilojoules. If we exceed our energy requirement by eating too much, irrespective of the fat, protein or carbohydrate content of the food, it will ultimately result in excess body fat.