Friend or Fad? continued...
Wiant points to several short-term studies that show the benefits of low-carb diets: quick weight loss and improved cholesterol levels. To counter the naysayers, he says there have been long-term studies (12 months long) of the diet that demonstrate sustained weight loss without increasing their risk of heart disease.
Yet Kantor expects research to someday catch up with the ills of low-carb diets. "In the long term, there is no question that low-carb diets will be shown to be dangerous," he says, noting that hundreds of epidemiological studies around the world have demonstrated that high-carbohydrate foods such as fruits, vegetables, and whole grains reduce risk of heart disease and prevent cancer.
Wiant responds in defense of low-carb diets. "It's irresponsible to conclude, based on the data out there, that the long-term studies will show some kind of huge reversal of [improved cholesterol] numbers," he says.
According to the National Center for Health Statistics, 64% of adults aged 20 years and older are overweight or obese, a 20% jump from the early 1960s. In preteens and teenagers, the numbers of overweight are both at 15%, compared with about 4% each 40 years ago.
Experts blame a sedentary lifestyle and bigger food portion sizes for the bulge. But there is also some finger pointing at the role of processed foods and junk food such as white breads, white rice, pasta, soda, chips, and cookies.
Wiant says many of the low-fat products caused weight gain because manufacturers added carbohydrates to the food to make up for the lack of fat.
Low-carb critics could apparently make the same argument. In order to replace carbohydrates, food makers have had to add fat, protein, fiber, water, or sugar-free sweeteners.
"You can't have a low-fat, low-carbohydrate, low-protein food, because then, what have you got?" says George Bray, MD, Boyd Professor in the division of nutrition and chronic diseases at the Pennington Biomedical Research Center in the Louisiana State University system. "Whenever someone lowers something, there's been a relative replacement by something else."