The moderate-fat diet, in which half the fat was monounsaturated fat from peanuts and peanut oil, produced a 14 per cent reduction in cardiovascular disease risk. The low-fat group experienced a 9 per cent improvement. Both the moderate and low fat diets were controlled so that all participants lost about the same amount of weight - approximately 2.4 to 2.7 pounds a week on average.
Dr Penny Kris-Etherton, distinguished professor of nutrition at Penn State university, said: "While the low-fat diet successfully reduced risk factors during the weight loss phase of the study, those factors rebounded during the maintenance phase."
The study, published in the February issue of the American Journal of Clinical Nutrition, involved 53 overweight or obese men and women with total cholesterol levels elevated above 200 at the start of the dieting.
The participants ate either a low-fat or moderate-fat diet designed to produce weight loss for six weeks and then similar diets designed for maintenance for four weeks. The foods were all provided by the researchers and provided 18 per cent of calories from fat in the low-fat diet or 33 per cent of calories from fat in the moderate fat diet.
Over the course of the study, the low-fat diet group experienced a 12 per cent decrease in HDL cholesterol but the moderate-fat diet group had no change. This indicates that a moderate-fat diet blunts the decrease in HDL cholesterol during weight loss.
In addition, after falling during the weight loss phase, triglycerides rose significantly during the maintenance phase for those on the low fat diet but not for those on the moderate fat diet. Elevated triglycerides are a cardiovascular risk factor.
"The findings of this current study are significant because they demonstrate that markedly lowering total fat intakes may have adverse consequences on reductions in the risk of CVD, even in response to weight loss," conclude the authors.
The World Health Organization has designated obesity as one of the most important public health threats because of the significant health impact of diseases associated with obesity such as cardiovascular disease. Cardiovascular disease kills more women around the world than any other disease.