A low-fat diet is a straightforward way to achieve a low-calorie diet, often used for weight loss, and it has the added benefit of controlling cholesterol.
Fat has more than twice the energy potential (calorie content) of either protein or carbohydrate and slightly more than alcohol. So, as a general rule, foods high in fat will also be high in calories. Most low-calorie diets take advantage of this fact and make a priority of lowering the intake of fat. This conveniently allows a low-calorie diet to also be low in fat, making it appropriate both for losing weight and lowering blood cholesterol.
A low-fat diet is made up primarily of foods that contain carbohydrates and fiber, including whole-grain breads and cereals, fruits, vegetables, and dried beans and peas. A low-fat diet should contain fewer foods from animal sources, which decreases saturated fat, or should replace them with foods that are low in fat or nonfat, such as nonfat or low-fat milk and yogurt.
In addition, a low-fat diet should contain more foods from plant sources, which provide fiber, are low in saturated fat, and do not contain cholesterol. Lean meats, poultry, fish, and low-fat or nonfat milk and yogurt supply protein.
Evidence suggests that low-fat diets result in weight loss primarily because the diets reduce total calories. However, studies show that people on low-fat diets not only lose weight but also benefit by lowering their total cholesterol, LDL cholesterol, and triglycerides. Moreover, in addition to the diet, exercise was shown to reduce cholesterol levels even more, as well as preventing a decrease in HDL cholesterol, which is often associated with low-fat diets. Evidence also suggests that a low-fat diet may offer some protection against certain types of cancer, such as breast and colon cancer.
A low-fat diet is generally defined as containing about 20 to 30 percent of calories from fat, but the Therapeutic Lifestyle Changes (TLC) program, which is recommended by the National Cholesterol Education Program and the American Heart Association for treating high blood cholesterol, allows 25 to 35 percent of calories from fat. This higher percentage of fat is permitted if most of the fat is of the heart-healthy variety -- polyunsaturated and monounsaturated -- and saturated fat and trans fat are kept low.
Moreover, increasing unsaturated fats in place of carbohydrates can help reduce triglycerides and raise HDL cholesterol in people with metabolic syndrome. In fact, research shows that in comparison to other types of diets, low-fat diets -- although effective at reducing body fat -- are not necessarily more effective than other weight-loss diets. In other words, a low-fat diet may not be the perfect fit for everyone; other diets that also reduce calories can result in weight loss as well.
If you choose to lose weight on a low-fat diet, cut back on -- but don't entirely cut out -- fat. Dietary fat is essential for the absorption of fat-soluble vitamins, such as A, D, E and K, and polyunsaturated fat provides essential nutrients, such as linoleic acid, which is needed for the production of a group of hormones called prostaglandins that regulate functions of the heart, blood vessels, kidneys, lungs, nerves, and reproductive organs, as well as for growth and healthy skin.
And, of course, fat adds flavor to foods. So add some fat, particularly monounsaturated and polyunsaturated fats, to your daily diet.
A more controversial type of diet is the low-carbohydrate diet, typified by the Atkins diet. Find out how this diet works on the next page.