Healthnotes Newswire (July 3, 2008)—Eating less and exercising more leads to weight loss. But does it matter which diet you follow? A new study suggests that it does: researchers found that a low-fat diet might be more effective than a low-carbohydrate diet at preventing cardiovascular disease in the long term, as it has better effects on the blood vessels.

Atkins vs. the American Heart Association

The study, published in Hypertension, included 20 obese but otherwise healthy adults who were assigned to eat either a low-fat diet or a low-carb diet for six weeks. The low-fat diet was based on the American Heart Association’s diet, which limits calories from fat to 30% of total calories. The low-carb diet was based on the Atkins diet in which only 20 grams of carbs (approximately the amount in one medium apple or two slices of whole-wheat bread) are allowed each day. The diets were designed to provide the same number of calories.

At the end of the study, people in both groups had lost about ten pounds, and blood pressures had decreased, though they were normal throughout the study. Vascular ultrasound showed that blood vessels dilated more readily in response to increases in blood flow after six weeks on the low-fat diet, indicating improved vascular health. In the low-carb group, this measure of blood vessel health had worsened.

Low-Fat Best for Heart Health, but Low-Carb Can Still Help

The low-carb diet was not without benefits, however. Fasting insulin levels decreased in this group, indicating that their insulin sensitivity and ability to control blood sugar had improved. This suggests that the relative benefits of the two diets might be different in people with diabetes. In addition, triglyceride levels, which are associated with heart disease risk, fell in the people consuming the low-carb diet.

Weight loss can help lower the risk of high blood pressure and hardened arteries (atherosclerosis) and their associated conditions: stroke and heart attack. People with obesity will benefit from losing weight, and a low-fat diet might be healthiest for their blood vessels. In addition, quitting smoking, exercising, and reducing stress can all contribute to a lower risk of cardiovascular disease and a healthier life.

Obesity is a major risk factor for cardiovascular disease, the number one cause of disability and death in the developed world. In response to rising obesity rates, weight-loss diets and fads continue to rotate through awareness and popularity. An estimated 45% of women and 30% of men in the United States diet to lose weight, but their choice of diets—and their results—vary widely.

“The composition of diet may be as important as the degree of weight loss in determining the effect of dietary interventions on dietary health,” said the study’s authors in their conclusion. “Low-fat diets may confer greater cardiovascular protection than low-carbohydrate diets.”

More information about the American Heart Association’s low-fat diet recommendations can be found at www.americanheart.org.

(Hypertension 2008;51:376–82)