The Evidence on Low-Carb Diets
Researchers hope studies currently underway will help answer some of those questions about the safety of low-carb diets. Until then, only short-term studies have addressed these issues.
A review of the research currently available on the safety and effectiveness of low-carb diets published last year in The Journal of the American Medical Association concluded that there was "insufficient evidence for or against the use of these diets."
"Despite the large number of Americans who have apparently adopted this approach to weight loss and/or weight maintenance, we know little of its effects or consequences," write researcher Dena Bravata, MD, of the Center for Primary Care and Outcomes Research at Stanford University and colleagues.
Some short-term studies have shown an improvement in cholesterol levels after six months on the Atkins diet. But Bravata's study showed that of the few low-carb studies that included information on cholesterol levels of the participants, there was no change in total, LDL ("bad") and HDL ("good") cholesterol levels. In contrast, the larger number of studies on higher-carbohydrate diets that included information on cholesterol levels showed a significant decline in total cholesterol levels.
Researchers say the lack of long-term data on low-carb diets severely limits their ability to evaluate their safety and effectiveness in promoting weight loss as well as reducing the risk of heart disease.
"The bottom line is that there is no single diet that is optimal for everyone," says Hu. "But if you choose the healthy sources of fats, carbohydrates, and protein, you can have many options to design a healthy diet not only for weight loss but also for the prevention heart disease and diabetes."