Overweight people who lose weight, especially abdominal fat, can improve the function of their blood vessels no matter whether they are on a low-carb or a low-fat diet. This data was presented by Johns Hopkins researchers at an American Heart Association scientific meeting in San Diego, CA.
In the six-month weight-loss study, the researchers found that the more belly fat the participants lost, the better their arteries were able to expand when needed, allowing more blood to flow more freely. Being overweight increases the risk of heart disease, especially if the fat is accumulated around the middle
Waist circumference is a measure of visceral fat, deep abdominal fat that packs itself around the organs. Visceral fat secretes chemicals that increase the body's resistance to the hormone insulin and cause inflammation throughout the body.
The researchers also found that participants who were on a low-carb diet lost about ten pounds more, on average, than those on a low-fat diet. After six months, those who were on the low-carb diet lost an average of 28.9 pounds versus 18.7 pounds among those on the low-fat diet.
The researchers studied 60 men and women who weighed an average of 215 pounds at the start of the program. Half of the participants went on a low-carb diet while the others followed a low-fat diet. All took part in moderate exercise and their diets provided a similar amount of calories each day.
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. This test can give an indication of the overall health of the vascular system throughout the body.
The more belly fat a person had lost, the greater the blood flow to the finger, signaling better the function of the artery.
The 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. The researchers say 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.
In the low-carb diet up to 30 percent of calories came from carbs such as bread, pasta and certain fruits, while 40 percent was from fat consumed from meat, dairy products and nuts. The low-fat diet consisted of no more than 30 percent of calories from fat and 55 percent from carbs.
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