The composition of the low-fat diet was 60 percent of calories from carbs, 20 percent from fat and 20 percent from protein. Although the lower-carb diet also had 20 percent of calories from protein, it had 45 percent from carbs and 35 percent from primarily unsaturated fats, such as nuts. Menus included a minimum of 2 fruits and 3 vegetable servings a day.

Use of prepared meals helped make the structured diets easier and more palatable for the dieters, according to Plodkowski. "We wanted to make this study real-world ”anyone could follow this plan by making moderate changes as part of a healthy menu," he said.

Both groups lost weight at each monthly weigh-in, but by 12 weeks, the insulin resistant group receiving the lower-carb diet lost significantly more weight, 19.6 pounds versus 16.2 pounds in the low-fat diet group - approximately 21 percent more on average.

"These data have potential widespread applications for clinicians when counseling people with insulin resistance to help improve weight loss as part of a calorie-restricted diet," Plodkowski said. "They should at least initially lower their carbohydrate intake."

SOURCE The Endocrine Society