The Lowdown on ‘Living Low Carb’
What the Experts Say About the Low-Carb Diet
Several clinical studies show that a low-carb diet can produce a greater initial weight loss than conventional low-fat diets; however, after one year, weight loss is similar with both diets. Weight loss from a low-carb or any kind of diet is a result of a lower caloric intake. Successful weight loss depends on lowering the intake of calories, increasing exercise, and making sure that all of the essential nutrients are consumed.
James Hill, PhD, director of the Center for Human Nutrition at the University of Colorado Health Sciences Center in Denver, says, "The problem I have with all the diets is not that people don't lose weight -- they do, and for some it feels like the greatest thing ever. My concern is that we have nothing to suggest that these diets work in the long term. This kind of research is missing."
Are these diets dangerous? "That's the debate going on today," Hill says. "All that protein really makes your kidneys work very hard. One school of thought is that the high-protein content of these diets is damaging to the kidneys." But, he adds, the most recent data shows that at least the "markers for kidney damage do not show a problem," and so, probably in the short term, these diets are not dangerous.
Another question, though, is whether the high-fat content of most of these diets is detrimental to our health, as high-fat diets have been shown to be factors in heart disease and some types of cancer. "For lower risk of cancer and other chronic diseases, the scientific evidence goes against the low-carbohydrate, high-protein diets," says Melanie Polk, RD, director of nutrition education at the American Institute for Cancer Research (AICR) in Washington, D.C.
In 1997, an AICR report reviewed some 4,500 diet and cancer studies from around the world comparing diet and cancer rates and found that a mostly plant-based -- in other words, high carbohydrate -- diet was protective against cancer and many chronic diseases. "Vegetables, fruits, and grains are foods low in protein but high in carbs, but also high in vitamins, minerals, phytochemicals, dietary fiber -- and we know all of these things are protective. Beans are high in vegetable protein but low in fat. We need to eat more plant-based food and less animal food, the exact opposite of a lot of these fad diets."
Another criticism of low-carbohydrate, high-protein diets has been the lack of food choices and the resulting difficulty that some people have staying within the limited choices over the long term. Both of McCullough's books help to provide a greater variety and more satisfying series of recipes and options for dining out. Experts, though, are still wary of promoting this form of low-carb diet until long-term studies can be completed.