Benefits of a Low-Carb Diet Beat Low-Fat in NIH Study
In the ongoing public debate between those who would have the world eat less fat and those who extol the virtues of a lower-carbohydrate diet, the carb detractors are celebrating a high-profile victory this week.
A new study financed by the National Institutes of Health and published in the Annals of Internal Medicine has added to a growing body of evidence that suggests those who avoid carbohydrates and eat more fat -- yes, even saturated fat -- lose more body fat and have a lower risk of cardiovascular ailments than people who follow the low-fat diet guideline health authorities have promoted for several decades.
The national focus on the harms of dietary fats, especially saturated fat, grew from studies in the middle of the last century that compared disease rates among significant national populations.
"To my knowledge, this is one of the first long-term trials that's given these diets without calorie restrictions," Dariush Mozaffarian, the dean of the Friedman School of Nutrition Science and Policy at Tufts University, said in a report by the New York Times.
"It shows," said Mozaffarin, who was not involved in the latest research, "that in a free-living setting, cutting your carbs helps you lose weight without focusing on calories. And that's really important because someone can change what they eat more easily than trying to cut down on their calories."
Since Dr. Robert Atkins popularized the approach in the 1970s, diets that are low in carbohydrates but higher in fat and protein have grown in popularity as a way to promote weight loss, despite the fact an army of nutritionists and health authorities have actively campaigned against low-carbohydrate diets, under the notion that cholesterol and other heart disease risk factors climb because low-carb dieters raise their intake of saturated fat by eating more meat and dairy, said the lead author of the new study, Lydia A. Bazzano of the Tulane University School of Public Health and Tropical Medicine.
"It's been thought that your saturated fat is, of course, going to increase, and then your cholesterol is going to go up," she told the New York Times.
The new finding, though, demonstrate that was not the case.
The research followed a very diverse group of 150 men and women who were assigned to follow diets for one year that either limited their intake of carbs or fat, but didn't put a cap on overall calories.
And, by the end of the year-long trial, subects in the low-carbohydrate group had lost an average of about eight pounds more than those in the low-fat group.
They also demonstrated significantly greater drops in overall body fat than the low-fat group, as well as marked increases in lean muscle mass, though neither group changed their levels of physical activity.
In fact, while those in the the low-fat group managed to lose weight, they appeared to have lost more muscle mass than fat, "which is a bad thing," Mozaffarian said.
"Your balance of lean mass versus fat mass is much more important than weight," she added, "and that's a very important finding that shows why the low-carb, high-fat group did so metabolically well."
The average consumer may not pay much attention to federal dietary guidelines, but their sway is substantial in government-funded activities, such as school breakfast and lunch programs, which is why many schools don't offer whole milk, but instead serve their students fat-free chocolate milk loaded with sugar, Mozaffarian said.