University of Michigan
Department of Pediatrics
Evidence-Based Pediatrics Web Site

Question

• In adolescent female patients, does a low carbohydrate diet promote weight loss as well as a low fat diet (current standard of care)?

Clinical Bottom Lines

1. No clinical actions should be taken with regard to the current fad of low-carbohydrate diets (Atkins diet) at this time.
2. Further study is necessary to determine appropriate use of these diets and appropriate monitoring of serum lipids.
3. Also, long-term compliance and efficacy needs to be studied further and in the pediatric patient population before this can be recommended as a first-line therapy for adolescent obesity.

Summary of Key Evidence

1. Thi study was designed "to compare the effects of a low-carbohydrate, ketogenic diet program with those of a low-fat, low-cholesterol, reduced-calorie diet."¹
2. Participants included patients 18-65 years old with BMI 30-60 and the desire to lose weight. Exclusion criteria were the presence of any serious medical condition, use of most prescription medicines within the previous 2 months, pregnancy, breastfeeding, recent dieting, and baseline ketonuria.
3. Study was randomized, but not blinded.
4. Primary outcome was weight loss while secondary outcomes included adherence to diet, ketonuria, body composition, vital signs, serum lipids and chemistries, and adverse effects of each diet.
5. Results at 24 weeks showed 12 kg weight loss (-12.9%) on the low-carbohydrate diet and 6.5 kg weight loss (-6.7%) on the low-fat diet.
6. Adverse events were more common in the low-carbohydrate group, and included constipation, headache, halitosis, muscle cramps, diarrhea, general weakness, and rash. In addition, two patients dropped out of the study for significantly elevated lipids.
7. Validity: study was appropriately randomized, but patients were not blinded; follow-up was good; and patients were analyzed in the groups to which they were randomized. While the groups were similar at the beginning of the trial, they received different instruction during each diet. For example, those in the ketogenic group were required to drink more water and take vitamin supplements.
8. Treatment results were significant: 3 patients needed to be treated with the Atkins diet instead of a low-fat diet to get one patient to lose >10% of body weight.
9. However, validity and need for long-term study suggest that results be taken with caution.

Additional Comments

• Study funding was provided by the Robert C. Atkins foundation.
• However, "the funding source had no involvement in the recruitment, interpretation of the data; or preparation or review of the manuscript."

Citation

1. Yancy WS Jr, Olsen MK, Guyton JR, Bakst RP, Westman EC. A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia: a randomized, controlled trial. Ann Intern Med 2004;140:769-77.

CAT Author: Patricia Keefer, MD

CAT Appraisers: Alex Kemper, MD

Date appraised: February 16, 2005