Study Finds Similar Weight Loss With Low-Carbohydrate Diet or Orlistat Plus Low-Fat Diet
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In the first randomized clinical trial to compare a low-carbohydrate diet with the combination of orlistat plus a low-fat diet, weight loss was similar for both approaches, but the low-carbohydrate diet was more effective for lowering blood pressure.
A total of 146 overweight or obese outpatients (mean age 52 years, mean body mass index 39.3) from the Department of Veterans Affairs primary care clinics in Durham, North Carolina, were assigned to one of two interventions:
• A low-carbohydrate diet that restricted carbohydrate initially to <20 g/day but did not restrict calorie intake.
• A low-fat diet (<30% energy from fat, 500-1000 kcal/day deficit) plus orlistat 120 mg before meals three times daily.
Participants in each group planned their own menus and were advised to exercise on their own for 30 minutes at least 3 times per week. They also participated in small group meetings every 2 weeks for 24 weeks, then every 4 weeks for 24 weeks.
Measurements were available at 48 weeks for 57 (79%) of participants in the low-carbohydrate diet group and 65 (88%) of participants in the orlistat plus low-fat diet group. Weight loss was significant and similar in both groups: participants who followed the low-carbohydrate diet lost a mean of 11.4 kg (9.5% of body weight), while participants who took orlistat in conjunction with a low-fat diet lost a mean of 9.6 kg (8.5% of body weight). There were no significant differences between the groups in fasting serum lipid or glycemic parameters. However, only participants in the low-carbohydrate diet group had reductions from baseline in systolic (−5.9 mm Hg) and diastolic (−4.5 mm Hg) blood pressure. Blood pressure increased slightly from baseline (1.5 mm Hg systolic and 0.4 mm Hg diastolic) among participants in the orlistat plus low-fat diet group.
The authors speculated that the beneficial effects on blood pressure seen with the low-carbohydrate diet might have been attributable to a diuretic effect.
Arch Intern Med. 2010;170(2):136-45.