Is a Low-Fat Diet Right for You?
Dietary fats are found in both plant and animal foods. Fat is one of three macronutrients that fuel your body, along with protein and carbohydrates. There are several types of fat, and some are more healthful than others.
The two most harmful varieties are saturated fat and trans fat. Saturated fat, which comes primarily from animal products like meat and milk, raises "bad" LDL cholesterol levels, and has been linked to increased risk of heart disease and type 2 diabetes. Trans fat, a manufactured fat produced when vegetable oil undergoes a process called partial hydrogenation, also bumps up LDL cholesterol and lowers "good" HDL cholesterol as well, further boosting the risk of heart disease.
Unsaturated fats, include monounsaturated and polyunsaturated, are healthier types. Monounsaturated fats are thought to improve levels of cholesterol and insulin and help control blood sugar. Sources include olive oil, oils derived from ground nuts, and avocados. Polyunsaturated fats, from sources including soybean oil and fatty coldwater fish, are rich in omega-3 fatty acids, which research suggests thwart heart disease and diabetes.
What's a low-fat diet?
Low-fat diets typically minimize saturated and trans fats and come in below the government's recommendation that 20 to 35 percent of daily calories come from fat. The Ornish diet, for example, which in some people has actually reversed heart disease, provides 11 to 16 percent of calories from fat; the Therapeutic Lifestyle Changes (TLC) diet, which is 22 percent fat, is at the low end of the recommended range. U.S. News has ranked those diets first and second, respectively, among diets best for the heart, and TLC is endorsed by the American Heart Association as a heart-healthy regimen.
What can I eat on a low-fat diet?
Think lean protein and lots of veggies. You'll load up on fruit, greens, low-fat dairy products, whole grains, fish, poultry, and nuts. High-fat dairy, such as butter, and fatty meats like salami are shunned.
How do low-fat diets work?
Low-fat diets are often designed to cut heart disease risk. Saturated and trans fat are thought to increase cholesterol levels and, thus, hike the odds of developing heart problems. By cutting back on these types of fat, heart benefits will likely follow. Weight loss is often an added bonus, especially since fat has about twice as many calories per gram as carbs and protein.
Will I lose weight on a low-fat diet?
Evidence suggests that low-fat diets promote weight loss. In one study, published in 2004 in the Annals of Internal Medicine, researchers tracked 120 overweight adults on a low-carb or low-fat diet for six months. By the study's end, the low-fat dieters had lost an average of 20 pounds—although low-carb dieters had lost even more, 31 pounds on average.
In a separate analysis of 19 clinical trials, researchers found that low-fat dieters lost significantly more weight than non-dieters—typically about 7 additional pounds per year, according to findings published in 2000 in the International Journal of Obesity. On average, researchers observed that reducing daily fat calories by 10 percent was associated with a loss of 6.3 pounds over six months.
Are low-fat diets risky?
Watching fat intake is smart, but your body needs some fat (the healthy kinds) to function at its best. Some vitamins require fat to dissolve and then nourish the body; if you don't get enough, you may become deficient in fat-soluble vitamins, like vitamins A, D, E, and K, and essential fatty acids. Most experts agree that low-fat diets are safe for people of all ages. Doctors sometimes even prescribe the low-fat TLC diet to obese kids to combat or prevent problems like type 2 diabetes and high cholesterol.
Popular Low-Fat Diets
U.S. News has profiled the following low-fat diet plans: