Overweight people are constantly being advised to take off the pounds. Failing that (and they often do), they might improve their health by limiting carbohydrates. That simple dietary change can lower levels of a particularly bad form of cholesterol linked to heart disease.
A study of moderately overweight men found that even without cutting calories, the fewer carbohydrates they ate, the lower the blood levels of what's called "small, dense low-density lipoprotein."
Low-density lipoprotein cholesterol is known as bad cholesterol. Among many subtypes of LDL, however, small, dense LDL is considered especially damaging to arteries (it's more likely to get into the artery wall and trigger plaque buildup).
Having lots of small, dense LDL, low levels of high-density lipoprotein (HDL or good cholesterol) and elevated triglycerides (another fat in the blood), is strongly linked to obesity, insulin resistance and diabetes and heart disease.
Dr. Ronald M. Krauss, director of atherosclerosis research at Children's Hospital Oakland Research Institute, studied 178 men who were on the path to becoming obese and diabetic. One group followed a 55% carbohydrate diet, approximating what most Americans eat. A second group ate 40% carbohydrates. A third group slashed carb intake to 25%; half of this group ate a diet heavy in the saturated fats found in meats and dairy foods, while the other half was encouraged to eat more monounsaturated fats, such as olive oil.
The 40%-carb group experienced a significant benefit in reduced small, dense LDL, Krauss told colleagues two weeks ago at the American Heart Assn. Scientific Sessions in Orlando, Fla. Restricting carbs to 25% brought further improvement, regardless of whether patients ate saturated or monounsaturated fats.
Unlike the Atkins diet, which virtually eliminates carbs, the test subjects were given more realistic carb reductions. For three weeks, they were told to maintain their weight while limiting carbs. Then for five weeks, everyone cut 1,000 calories a day. All the men lost weight and reduced bad cholesterol, but those on the 25% carb diet already had gotten big reductions in the bad cholesterol before cutting calories. The others' cholesterol dropped once they cut calories.
Carolyn Berdanier, a University of Georgia nutritionist, said that carb reductions might not have the same effect on everyone because of genetic differences.