Insulin-resistant obese women lost more weight after 12 weeks on a low-carbohydrate diet than they did on a low-fat diet, according to a study conducted by the University of Nevada School of Medicine in Reno. (The study was funded by Jenny Craig, a company that sells diet foods.)
The two diets, which had the same calorie counts, were followed for nearly three months by 45 insulin-resistant obese women between the ages of 18 and 45. The women were divided randomly into two groups. The group assigned to the low-fat diet averaged 213 pounds per member, while the low-carb diet group averaged 223 pounds per member.
The low-fat diet derived 60 percent of its calories from carbohydrates, 20 percent from protein, and 20 percent from fat. The low-carb diet, which was actually a “lower-carb” diet, derived 45 percent of its calories from carbohydrates, 20 percent from protein, and 35 percent from mostly unsaturated fats such as nuts. Both diets required study subjects to eat a daily minimum of two servings of fruit and three servings of vegetables.
By the end of the study, the women eating the low-carb diet had lost an average of 3.4 pounds more than the women eating the low-fat diet-19.6 pounds versus 16.2 pounds.
The study’s lead author, Raymond Plodkowski, MD, chief of endocrinology, nutrition, and metabolism at the school, said that while low-fat diets are more often prescribed by doctors to help overweight patients shed pounds, low-carb diets seem to be more effective, at least in the short term, at helping dieters overcome insulin resistance.
Insulin resistance often shows up in older and overweight people. Their bodies lose the ability to use insulin properly to metabolize glucose, which leads to a potentially damaging build-up of sugar in the blood, as well as weight build-up or retention. A high-carbohydrate diet complicates matters by presenting the body with an overabundance of the nutrient it is least capable of metabolizing efficiently. Lowering carb intake gives the body a better chance to metabolize carbohydrates properly.
Plodkowski’s study is one more indicator that the primacy of the low-fat diet as the initial weight-loss recommendation of healthcare providers is nearing an end. For people with diabetes and pre-diabetes, carbohydrates have always been a concern because they are the food that does the most to bring on problems with high blood sugar and overweight. The trend now, says Plodkowski, is for clinicians to recommend lower carbohydrate intake from the start.