Study explains low-carb diets’ fast results
A new study by School of Medicine researchers has shown why the pounds melt away so quickly on low-carbohydrate diets — and it’s not related to water, metabolism or boredom with diet. The research was conducted in a group of obese patients with type-2 diabetes who followed the Atkins diet.
According to lead researcher Guenther Boden, “When carbohydrates were restricted, study subjects spontaneously reduced their caloric intake to a level appropriate for their height, did not compensate by eating more protein or fat, and lost weight. We concluded that excessive overeating had been fueled by carbohydrates.”
Almost 80 percent of diabetics are overweight or obese, compounding health risks such as heart disease and stroke. Boden wanted to examine how low-carbohydrate diets, which have been shown to produce rapid weight loss, affected weight, appetite and blood sugar in obese diabetics.
He discovered that study subjects did not eat less because they were bored with the food selection, and their weight loss was not attributable to water loss, two common speculations about low-carb diets. Further, weight loss could not be explained by a change in metabolism, another popular misconception.
The study, “Short-term effects of low-carbohydrate diet compared with usual diet in obese patients with type 2 diabetes,” is published in the March 15 issue of the Annals of Internal Medicine. It is the only study of the Atkins diet to have been conducted in the strictly controlled environment of a clinical research center where every calorie eaten and spent was measured.
After a week of typical eating, 10 obese patients with type-2 diabetes followed the Atkins diet for two weeks, with carbohydrates limited to 20 grams per day and unlimited protein and fat.
“When we took away the carbohydrates, the patients spontaneously reduced their daily energy consumption by 1,000 calories a day. Although they could have, they did not compensate by eating more proteins and fats, and they weren’t bored with the food choices. In fact, they loved the diet. The carbohydrates were clearly stimulating their excessive appetites,” Boden said.
All patients stayed in the hospital for the length of the study to ensure exact measurements of calorie intake and expenditure. In other studies of the Atkins diet, subjects were at home and reported their own diet and exercise, making it difficult to ensure accuracy.
In addition to the calorie reduction and weight loss, subjects experienced markedly improved glucose levels and insulin sensitivity, as well as lower triglycerides and cholesterol.
Treatment for diabetes centers on closely monitoring sugar levels, diet and medication. Weight loss can often reduce or eliminate the need for medication, including insulin.
Boden warned that the long-term effects of low-carbohydrate diets are not known. Whether other types of diets would have a similar impact also remains to be investigated.
Other research projects of Boden’s include a National Institutes of Health-supported study of obesity-associated diabetes and cardiovascular disease.
This study was funded by grants from the National Institutes of Health and the American Diabetes Association.
- By Eryn Jelesiewicz