Flawed Reanalysis Fails to Support the Carbohydrate-Insulin Model of Obesity

A recent reanalysis of publicly available data claimed that the carbohydrate-insulin model was supported by results from a randomized crossover trial comparing low carbohydrate (LC) versus low fat (LF) diets. The reanalysis also claimed to have invalidated the primary outcome of the trial, namely the within-participant differences in ad libitum energy intake when they consumed LC vs LF diets. Here, we demonstrate that both claims are untrue. The reanalysis was fatally flawed in several respects, with the most egregious errors related to ignoring the within-participant, repeated-measures structure of the data and treating data timepoints as independent. This resulted in almost all statistical comparisons being incorrect and reporting wildly optimistic p-values. Furthermore, the authors failed to engage sufficiently with prior work on the same trail data and portrayed their reanalysis as being more novel than it was. The reanalysis also failed to disclose the possibility of bias and succumbed to common statistical errors that falsely led the authors to interpret the data as supporting the carbohydrate-insulin model of obesity.