Total fat tells you the amount of fat in each serving of a food item. This number includes both healthy fats (monounsaturated, polyunsaturated) as well as unhealthy fats (saturated, transfat). Fat has 9 calories per gram, more than twice the calories per gram of carbohydrates and proteins.
If you are trying to lose weight, you should limit the amount of fat that you eat. Choose foods that are lower in fat, such as skim milk instead of two-percent milk. However, it is important to be aware that foods labeled "fat-free" are not calorie-free. Often times, manufacturers add sugar to these products in place of the fat.
Saturated fat and “lousy cholesterol” levels (7)
The lowdown on transfat (8)