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
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.
was randomized, but not blinded.
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.
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.
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.
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
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
validity and need for long-term study suggest that results be taken