A recent paper intended as a systematic review concluded, "weight loss while using low-carbohydrate diets was principally associated with decreased caloric intake and increased diet duration, not with reduced carbohydrate content [
14]." As pointed out by Kauffman [
15] however, in the true low-carbohydrate group in the study, the mean weight loss in trials was 17 kg, while in the higher-carbohydrate group it was only 2 kg. Oddly enough, the authors did not consider this significant. As Kauffman pointed out, "
the conclusions should have been that low-carbohydrate diets are both safe and effective[
15]." Only by intermingling trials of low to medium and high-carbohydrate diets could the authors reach the misleading conclusion quoted above [
15]. A recent report by Foster et al. concluded that a low-carbohydrate diet produced a greater weight loss than did the conventional diet for the first six months, although the differences were not significant at one year [
16]. Samaha et al. randomly assigned 132 severely obese subjects to a low-carbohydrate or calorie and fat-restricted (low-fat) diet [
17]. Seventy-nine subjects completed this six-month study. It should be noted that the difference in consumption of energy from carbohydrate was quite narrow: 51% in the low-fat group and 37% in the low-carbohydrate group. Total energy intake at the 6-month mark was 1567 kcal/day in the low-fat group and 1630 kcal/day in the low-carbohydrate group. Thus, the low-carbohydrate group consumed 54 extra kcal/day. Nevertheless, the low-carbohydrate group lost 5.8 kg (and was still losing weight at 6 months) vs. 1.9 kg (leveled off) in the low-fat group. Both groups were given an exceptional number of contacts with "experts in nutritional consulting", so the possible placebo and nocebo effects would be even more intense here [
18]. Greene et al. found that people eating an extra 300 kcal a day on a very-low-carbohydrate diet lost a similar amount of weight during a 12-week study as those on a low-fat diet [
19]. Over the course of the study, subjects consumed an extra 25,000 kcal that should have added up to about a 7 pounds weight gain; it did not. The study was unique because all the food was prepared at an upscale Italian restaurant, so the researchers knew exactly what they ate, and one could not argue that diets were not palatable. Finally, a recent randomised, balanced, two diet study compared effects of isocaloric, energy-restricted ketogenic and low-fat diets on weight loss and body composition in overweight/obese men (n = 15) and women (n = 13) [
20]. Despite significantly greater calorie intake (1855 vs. 1562 kcal/day), both between and within group comparison revealed a distinct advantage of a ketogenic diet over a low-fat diet for weight loss/fat loss for men. In fact, 5 men showed more than 10 pounds difference in weight loss. Majority of women also responded more favourable to the ketogenic diet, especially in terms of trunk fat loss. Furthermore, the individual responses revealed that three men and four women who did the ketogenic diet first, regained body mass and fat mass after the switch to the low-fat, whereas no subjects regained weight or fat mass after switching to the ketogenic diet.