Function: Fat is the body's major energy storage system. When the body does not use energy, it may be saved as fat for later usage. The body uses fat as energy, to cushion organs and bones, and to make hormones and regulate blood pressure. Some fat is also essential in maintaining healthy skin, hair and nails.

Types of Fats: Not all fat is the same, either. Saturated fats are the kind that are generally solid at room temperature and are the least healthy. They increase cholesterol levels in the blood and should be limited and closely monitored in anyone's diet. Saturated fats come from butter, cheese, shortening, some margarine, tropical oils and the fats in meat and poultry skin. Unsaturated fats are generally regarded as the healthier type of fat, and they are good when they replace saturated fats in the diet. However, there are also two different types of unsaturated fats. Monounsaturated fats have been shown to increase levels of HDL cholesterol in the blood, the "good" cholesterol that helps to prevent heart attacks. In moderation, monounsaturated fats can be a healthy part of your diet. Peanut butter, olive oil and canola oil are particularly high in monounsaturated fat. On the other hand, polyunsaturated fats are more likely to form free radicals and damage tissue. They come from plants and high-fat fish such as tuna and salmon.

Recommended Daily Amount: SparkPeople (along with the American Heart Association and the USDA) recommends that people get less than 30% of calories from fat.  Of that 30%, no more than 10% should come from saturated fat.   Each gram of fat consumed has 9 calories, over twice as many as a gram of carbohydrates or protein has. For a 2,000-calorie a day diet no more than 66 grams of fat (600 fat calories) should be consumed. Your fat recommendation is based on your calorie goals.

If you wish to use up your body's fat, it is important to limit intake of high-fat foods and exercise moderately. This will improve metabolism and keep calories down. Regular aerobic exercise is a great way to work fat. Also, building muscle through strength training is a good way to burn more calories. Muscle burns more calories than fat, so they more muscle you have, the more calories you burn.