The striking data tabulated by Krauss, et al. [1
] and presented in graphic form in Figures , , , , are somewhat at odds with their stated conclusion: "Moderate carbohydrate restriction and weight loss provide equivalent but non-additive approaches to improving atherogenic dyslipidemia" and "the beneficial lipid changes resulting from a reduced carbohydrate intake were not significant after weight loss."
It is not clear what is meant by additive since the combined effects due to macronutrient change and caloric restriction are not compared to experiments where they are implemented together which are known to provide large positive effects. In any case, at least HDL values do show significant increases in both phases of the experiment, positive for low carbohydrates, initially negative and then positive for low fat and there is a pronounced additive effect (Figure ).
Compared to weight loss on a LF diet, the high saturated fat CR diet with no weight loss resulted in better improvements in LDL peak size, TAG, HDL, and the ratios total cholesterol/HDL and apoB/ApoA-1, that is, the effects are not equivalent; CR is significantly better than weight loss in the presence of LF for atherogenic dyslipidemia. The fact that these effects are not equivalent is further shown in Figures , , , , , where the combined (weight stable and weight loss) effects for LF are not as great as for CR. The results suggest that if, at week 12, a 26 % CR with saturated fat were instituted for the LF group, further improvement in lipid profile would be brought about.
Krauss et al. [1
] make the underlying assumption that weight loss is the same whether caused by caloric restriction in the presence of low carbohydrate or low fat but their data show that this is not so. It seems that they also assume that weight loss is a cause not an effect (due to calorie reduction). Whereas this may play a role, it is reasonable to assume that improvement in dyslipidemia and
weight loss are parallel responses
to calorie reduction which is the major physiologic stimulus. It is obvious that the reason lipid changes are not brought about in Krauss's experiment by weight loss in the low carbohydrate arms is that the lipid markers have already changed drastically. Finally, it should be pointed out that the reduction in calories that is effective in the weight loss phase of the low fat arm included a substantial reduction in carbohydrate as one component.