People who avoid carbohydrates and eat more fat, even saturated fat, lose more body fat and have fewer cardiovascular risks than people who follow the low-fat diet that health authorities have favored for decades, a major study shows.
More recent clinical studies in which individuals and their diets were assessed over time have produced a more complex picture. Some have provided strong evidence that people can sharply reduce their heart disease risk by eating fewer carbohydrates and more dietary fat, with the exception of trans fats. The new findings suggest that this strategy more effectively reduces body fat and lowers overall weight.
The study was financed by the National Institutes of Health and published in the Annals of Internal Medicine. It included a racially diverse group of 150 men and women — a rarity in clinical nutrition studies — who were assigned to follow diets for one year that limited either the amount of carbs or fat that they could eat, but not overall calories, the Boston Globe reports.
By the end of the yearlong trial, people in the low-carbohydrate group had lost about 8 pounds more on average than those in the low-fat group. They had significantly greater reductions in body fat than the low-fat group and improvements in lean muscle mass — even though neither group changed its levels of physical activity.
While the low-fat group lost weight, members appeared to lose more muscle than fat.
Overall, the low-carb participants took in a little more than 13 percent of their daily calories from saturated fat, more than double the 5 percent to 6 percent limit recommended by the American Heart Association. The majority of their fat intake, however, was unsaturated fats.
In the end, people in the low-carbohydrate group saw markers of inflammation and triglycerides — a type of fat that circulates in the blood — plunge. Their HDL, the so-called good cholesterol, rose more sharply than it did for people in the low-fat group.
Blood pressure, total cholesterol, and LDL, the so-called bad cholesterol, stayed about the same for people in each group. Nonetheless, those on the low-carbohydrate diet ultimately did so well that they lowered their Framingham risk scores, which calculate the likelihood of a heart attack within the next 10 years. The low-fat group on average had no improvement in its scores.