Low-Carb, Higher-Fat Diets Add No Arterial Health Risks to Obese People Seeking to Lose Weight

Overweight and obese people looking to drop some pounds and considering one of the popular low-carbohydrate diets, along with moderate exercise, need not worry that the higher proportion of fat in such a program compared with a low-fat, high-carb diet may harm their arteries, suggests a new study by heart and vascular researchers at Johns Hopkins.

“Overweight and obese people appear to really have options when choosing a weight-loss program, including a low-carb diet, and even if it means eating more fat,” says the studies’ lead investigator exercise physiologist Kerry Stewart, EdD.

Stewart, a professor of medicine and director of clinical and research exercise physiology at the Johns Hopkins University School of Medicine and its Heart and Vascular Institute, says his team’s latest analysis is believed to be the first direct comparison of either kind of diet on the effects to vascular health, using the real-life context of 46 people trying to lose weight through diet and moderate exercise. The research was prompted by concerns from people who wanted to include one of the low-carb, high-fat diets, such as Atkins, South Beach and Zone, as part of their weight-loss program, but were wary of the diets’ higher fat content.

In the first study, presented at the annual meeting of the American College of Sports Medicine, the Hopkins team studied 23 men and women, weighing on average 218 pounds and participating in a six-month weight-loss program that consisted of moderate aerobic exercise and lifting weights, plus a diet made up of no more than 30% of calories from carbs. As much as 40% of their diet was made up of fats coming from meat, dairy products, and nuts. This low-carb group showed no change after shedding 10 lbs in two key measures of vascular health: finger tip tests of how fast the inner vessel lining in the arteries in the lower arm relaxes after blood flow has been constrained and restored in the upper arm (the so-called reactive hyperemia index of endothelial function), and the augmentation index, a pulse-wave analysis of arterial stiffness.

Low-carb dieters showed no harmful vascular changes, but also on average dropped 10 lbs in 45 days, compared with an equal number of study participants randomly assigned to a low-fat diet. The low-fat group, whose diets consisted of no more than 30% from fat and 55% from carbs, took on average nearly a month longer, or 70 days, to lose the same amount of weight.

“Our study should help allay the concerns that many people who need to lose weight have about choosing a low-carb diet instead of a low-fat one, and provide reassurance that both types of diet are effective at weight loss and that a low-carb approach does not seem to pose any immediate risk to vascular health,” says Stewart. “More people should be considering a low-carb diet as a good option,” he adds.

Because the study findings were obtained within three months, Stewart says the effects of eating low-carb, higher-fat diets vs. low-fat, high-carb options over a longer period of time remain unknown.

However, Stewart does contend that an over-emphasis on low-fat diets has likely contributed to the obesity epidemic in the United States by encouraging an over-consumption of foods high in carbohydrates. He says high-carb foods are, in general, less filling, and people tend to get carried away with how much low-fat food they can eat.

Source: Johns Hopkins Medicine