But there was a catch. Blood samples taken while participants were on the low-carb diet revealed spikes in cholesterol and other measures of heart disease, stroke and even diabetes risk. [7 Foods Your Heart Will Hate]
The low-glycemic-index diet offered the best in terms of modest improvement in metabolism and reducing the risk of various chronic diseases, Ludwig told LiveScience. The low-fat diet — what's recommended by the U.S. government and the American Heart Association — performed the worse, Ludwig added, because it decreased the metabolism rate and raised the risk for diabetes and metabolic syndrome.
Processed vs. non-processed
At first glance, this study might appear to rule out a so-called "low-fat" diet. Not so, says Dean Ornish, founder of the Preventive Medicine Research Institute in Sausalito, Calif., and of the low-fat diet that bears his name.
"The choice is not between a diet that is low in fat yet high in sugar versus one that is low in sugar but high in fat, or an in-between diet," Ornish told LiveScience. "An optimal diet is predominantly whole foods that are low in fat and low in sugar and [low in] other high-glycemic-index foods," a diet he has long advocated.
Ludwig agreed that a low-fat diet could work provided that the carbohydrate component of the diet is low on the glycemic index. But this is complicated in an American diet, he said, because even whole grains, when heavily processed, can spike the blood sugar. Soft, whole wheat bread can have an identical glycemic index profile as white bread.
"We believe that low-glycemic-index diets are easier to stick to on a day-to-day basis, compared to low-carb and low-fat diets, which many people find limiting," said Ebbeling. "Unlike low-fat and very-low-carbohydrate diets, a low-glycemic-index diet doesn't eliminate entire classes of food, likely making it easier to follow and more sustainable."
"The focus on fat reduction is a waste of energy," added Ludwig. "Low-carb has downsides, too."
Copyright 2012 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. ]]>