Although the patients liked the food - eggs, bacon and link sausage for breakfast, for example - they cut back on daily intake by about 1,000 calories. At baseline the volunteers were all consuming an average of 3,111 calories. "They each cut back to about 2,100 calories, which, as it turns out, was the exact amount they should be consuming based on their height and age," Boden said.

As a result they each lost about 3.6 pounds and improved their blood glucose levels.
"Carbohydrates appear to drive both appetite and blood sugar," he said.

· Mean fasting plasma glucose decreased from 135 mg/dL on day 8 to 113 mg/dL on day 22 (p=0.025)
· Serum triglycerides decreased by 35% from 162.83 ± 5.58mg/dL to 105.31 ± 2.65 mg/dL (p<0.001).
· Total cholesterol decreased from 180 mg/dL to 163 mg/dL (p<0.02).
· No significant differences in HDL or LDL.

During the first week of the 3-week study, the volunteers ate a regular diet with no restrictions. For the next two weeks they were put on an Atkins induction diet, which limits carbohydrates to 20 grams per day.

It was well known that a low-carb diet can rapidly take off pounds, but Dr. Boden said that until his study, "there was disagreement about what caused the weight loss: was it just water weight, or did people burn off more energy with protein, or was it that something special about calories from carbohydrates that made them trigger more weight gain? It turns out that it is very simple - people just eat less when you take away the carbohydrates."

But while this approach works in the short term, Boden said he doesn't think it can be sustained over the long haul. Rather than eliminating carbohydrates or restricting diets to 20 grams of carbs, he suggests a simpler approach: "take one potato instead of two or three, one slice of bread rather than three and stay away from desserts."

In an editorial that accompanied the study, George A. Bray, MD, chief of clinical obesity and metabolism at the Pennington Biomedical Research Center in Baton Rouge, La., commended Dr. Boden for a "nicely done, short-term metabolic ward study." But Dr. Bray said that he is not convinced that "that one diet has any more value than another - they all have value."

· Advise patients that this small study suggests that low carb diets may be effective for short term weight loss, but their long term efficacy was not studied.