Abstract
The question of whether the ratio of dietary carbohydrates to fat substantially impacts total energy expenditure (TEE) or body fat has been investigated for decades, with most studies pointing to no clinically meaningful effect. However, a recent study by Ebbeling et al. (https://doi.org/10.1136/bmj.k4583) reported substantial differences in TEE between diets varying in their ratio of carbohydrate to fat. The original pre-registered statistical analysis plan for the primary study outcome of Ebbeling et al. addressed the question of whether the reduction in TEE during weight loss maintenance compared to the pre-weight loss baseline depended on the dietary carbohydrate to fat ratio. However, the final analysis plan was modified to make the diet comparisons with the TEE measurements collected in the immediate post-weight loss period rather than at the pre-weight loss baseline. Here, we reanalyzed the data according to the original plan we found that the TEE differences were no longer statistically significant between the diet groups and the nominal diet differences of ∼100 kcal/d were much smaller than the ∼250 kcal/d differences reported in the publication. In other words, when conducting the analysis originally planned by the authors we found that the significant increases in TEE with the low carbohydrate diet that were reported by Ebbeling et al. disappeared. Furthermore, the TEE effect modification by baseline insulin secretion also disappeared.