I came across this report yesterday. It concerns a study presented at the American Heart Association meeting in San Diego this week. From the report it appears that overweight individuals were randomised to one of two diets for 6 months (along with moderate exercise).
‘low-carb’: 30, 40, 30 per cent of calories from carbohydrate, fat and protein respectively
‘low-fat’: 55, 30, 15 per cent of calories from carbohydrate, fat and protein respectively
Those on the low-carb diet lost a lot more weight than those on the low-fat diet – about 29 lbs (13 kg) v 19 lbs (8.5 kg).
The study participants were also tested for a measure of health in the cardiovascular system known as ‘flow mediated dilatation’ (FMD). Here’s how the report I’ve linked to describes this test and the results:
In order to evaluate the health of the participants’ blood vessels before and after the weight loss program, the researchers conducted a blood flow test by constricting circulation in the upper arm for five minutes with a blood pressure cuff. With this type of test, when the cuff is released, a healthier artery will expand more, allowing more blood to flow through the artery. The researchers measured how much blood reached the fingertips before, during, and after the constriction of the artery. Stewart (Kerry J Stewart – professor of medicine at the Johns Hopkins University School of Medicine) says this test can give an indication of the overall health of the vascular system throughout the body. The researchers found that the more belly fat a person had lost, the greater the blood flow to the finger, signalling better the function of the artery.
Professor Stewart goes on to say that:
Our study demonstrated that the amount of improvement in the vessels was directly linked to how much central, or belly fat, the individuals lost, regardless of which diet they were on. This is important since there have been concerns that a low-carb diet, which means eating more fat, may have a harmful effect on cardiovascular health. These results showed no harmful effects from the low-carb diet.
Many studies have now pitted low-fat against low-carb diets in terms of weight loss and disease markers, and low-carb reigns victorious. Unless, of course, you’d prefer to discount all this good, clinical evidence in humans in favour of experiments done in genetically manipulated mice. See here.