More weight lost on low carb than low fat

FRIDAY, MAY 21, 2004

Two new studies published in the Annals of Internal Medicine have found low carb dieting to be more effective for weight loss than low fat.

In one study, 120 overweight volunteers followed the diets over a 24-week period while in the other study, 132 obese adults (with a body mass index of 35kg/m² or greater) were tested.

Low-carb dieters in the overweight study lost an average of 9.4kg body fat compared to 4.8kg for low fat. In the obese group, low carb dieters lost an average 5.1kg weight compared to 3.1kg for low fat.

The research team behind the overweight study, led by Dr William Yancy from Duke University, North Carolina, found that the low-carb participants were voluntarily eating fewer calories, possibly due, they said, to the diet's appetite-suppressant properties.

"The voluntary reduction in energy intake among recipients of the low carbohydrate diet merits future research," they said.

The obesity study, led by Dr Linda Stern from the University Of Pennsylvania, made similar observations.

"Our data suggest that weight loss differences may be explained by lower caloric intake on a low-carbohydrate diet. If true, this may be attributable to the simplicity of a low-carbohydrate diet or to greater effects on satiety."

Satiety, the "full" feeling after eating a meal, is currently at the centre of obesity and weight management research as the role of appetite in maintaining a diet becomes increasingly evident.

Rates of compliance were also observed in both studies.

In the overweight study, 76 percent of low-carb participants stuck to their diet for the duration of the study whereas 57 percent persisted in the low fat group. Researchers said that most of the low-fat dropouts had less weight loss than their peers which may have contributed to their decision.

In the obese study, 34 percent of all participants dropped out with many unable to meet their dietary targets during the study. Meeting these targets might have produced different results, researchers noted.

While cholesterol profile improved among the low carb dieters in both studies, a number of adverse reactions were recorded in the overweight study, with low carb not comparing favourably to low fat. Complaints included constipation (68 compared to 35 percent), headache (60 and 40 percent), halitosis (38 and 8), muscle cramps (35 and 7), diarrhea (23 and 7), general weakness (25 and 8), and rash (13 and 0).

This study also found that the low-carb group lost a greater amount of water in the first two weeks than the low fat.