Are Low-fat Diets Good for Promoting Weight-loss?

Are low-fat diets actually good for weight-loss?

Low-fat diets became popular in the 70’s and 80’s with the idea that fat would cause weight gain and heart disease. Many consumer books fueled the fire, and eventually thousands of individuals were seeking to reduce the amount of fat they ate as a way to improve health. By the 1990s, the federal government had updated the Food Pyramid to include low-fat, high-starch foods.

Low-fat Diets: A Brief Synopsis

Dietary guidelines for Americans generally recommend that 20 to 35 percent of daily calories come from fat. While the true definition of a low-fat diet is debated, most resources call for a diet with less than 30 percent of total calories coming from fat each day. The Therapeutic Lifestyle Change (TLC) Diet, supported by the American Heart Association, recommends 22 percent fat or less. On the more extreme end, the Ornish Diet recommends less than 10 percent.

How Low-fat Diets Work

The basic theory of a low-fat diet is that fat at nine calories per gram has a lot more calories than carbs or protein. Also, reducing dietary fat will likely reduce intake of trans fats, saturated fats and dietary cholesterol which may have independent health risks. Because dietary fats and protein are often found together in foods (think steak, cheese, whole eggs, etc…), low-fat diets are relatively high in carbs and lower in protein than in other diets. Many low-fat diets are very close to vegetarian diets for this reason.

Comparing Popular Diets

Despite the craze for high-protein, carb-restricted diets, much research supports low-fat diets. This is partly why the debate rages on. In studies that have looked at low-fat diets vs. low-carb diets, both tend to produce weight-loss (thought in the short term, low-carb diets may produce more).

It is worth nothing that the largest study of a low-fat diet for weight-loss (The Women’s Health Initiative Dietary Modification Trial – which looked at 19,500 women for eight years) did not show any benefits for heart disease, cancer or weight as compared to an unrestricted diet. However, while the goal for the trial was for women to eat 20 percent of total daily calories from fat, participants actually only reached 29 percent. Thus, it’s possible that the lesson here is that having a goal of 20 percent calories or less is hard to achieve.

Risks of Low-fat Diets

Basic risks of low-fat diets include eating too many calories from simple carbohydrates (sugars and other empty calorie foods) and missing out on good or essential fats and fat-soluble vitamins. However, fat-restricted diets have clear medical benefits for those with a medical condition where fat is hard to digest. This can include gallbladder disease, chronic pancreatitis or malabsorption.

In Health,

Dr. Jacques

About the Author

Dr. Jacques, a frequent author in the Obesity Action Coalition’s (OAC) quarterly publication, Your Weight Matters Magazine, is a Naturopathic Doctor with more than a decade of expertise in medical nutrition. She is the Chief Science Officer for Bariatric Advantage (a Division of Metagenics, Inc), a company dedicated to providing the best of nutritional care to weight-loss surgery patients. Her greatest love is empowering patients to improve their own health. 

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