Low Carbohydrate Dieting Increases Weight Loss but not Cardiovascular Risk in Obese Adolescents: A Randomized Controlled Trial
Sondike, S.B., Copperman, N.M., Jacobson, M.S., "Low Carbohydrate Dieting Increases Weight Loss but not Cardiovascular Risk in Obese Adolescents: A Randomized Controlled Trial," Journal of Adolescent Health, 26, 2000, page 91.
This study tested whether a low-carbohydrate diet that did not restrict calories would be more successful in promoting weight loss than a low-fat, low-calorie diet. Researchers also tested to see if such a diet would have negative effects on blood lipid profiles, thus increasing cardiovascular risk. To test their hypothesis, they recruited 39 obese adolescents for the study; 20 were placed in a low-carbohydrate diet group while 19 were placed in a low-fat diet group. Subjects in the low-carbohydrate group were allowed to consume as much protein and fat as they wanted, so long as carbohydrate intake remained below 20 grams for the first two weeks and below 40 grams for the next nine weeks. Members of the low-fat group were instructed to consume fewer than 40 grams of fat per day. The low carbohydrate group participants consumed an average of 1,830 calories per day while those in the low-fat group consumed 1,100 calories per day. Both groups showed improvement in HDL ("good") cholesterol, triglycerides and total cholesterol. The improvement in triglycerides was much more pronounced in the low-carbohydrate group. Eating 700 more calories per day than the low-fat group, the low-carbohydrate group lost twice as much weight (an average loss of 48 pounds for the low-carbohydrate group versus an average of 20 pounds for the low-fat group). Neither diet had any effect on liver or kidney function. The researchers concluded that the low-carbohydrate diet significantly improved weight loss despite a higher caloric intake. Also, contrary to their hypothesis, despite increased fat intake, the cardiovascular risk profile did not worsen, but in fact improved in certain aspects including HDL cholesterol and triglycerides.