Low-carb diet leads to fastest weight loss among obese women, study says

• Obese women who follow low-carbohydrate diets, such as the Atkins diet, may lose more weight in a four-month period than those who go on low-fat diets, new study findings show.
• The reason for the greater weight loss, however, is not clear.
• In a previously published study, Brehm and her colleagues compared the effects of a low-carbohydrate diet versus a low-fat diet among obese women.
• They found that the women on the low-carbohydrate diet lost more than twice as much weight as those in the comparison group during a six-month study period.
• The researchers hypothesized that the greater weight loss among those on the low-carbohydrate diet was due to the women's greater energy expenditure.
• "If it's not calories in, it must be calories out," Brehm told Reuters Health.
• By the end of the four-month study, women in both groups had lost weight and body fat, the researchers report in this month's issue of the Journal of Clinical Endocrinology and Metabolism.
• However, the low-carbohydrate group lost more than 10 percent of their body weight, while the low-fat group lost about 7 percent.
• Specifically, the low-carbohydrate group lost 9.8 kilograms (21.6 pounds) of weight and 6.2 kilograms (13.7 pounds) of body fat, while the low-fat group lost about 6.1 kilograms (13 pounds) of weight and 3.2 kilograms (7 pounds) of body fat, the report indicates.
• To estimate their level of physical activity, women in both groups were fitted with pedometers, which recorded the number of steps they took daily.
• At the start of the study, both groups of women had similar pedometer readings, and by the end of the study, there were no significant changes, according to Brehm and her team.
• The thermic effect of food (TEF), which comprises up to 10 percent of the amount of energy consumed daily, includes the energy expended during digestion.