I would not believe that unless you have done a simulation study with the small n of this study, plausible levels of measurement error (alcoholism being much harder to measure than weight or body fat), with about a dozen covariates (to correspond to the different ways to slice the patients and threshold BMI etc), and then shown that you hardly ever get a false negative like this. My experience with doing such power analysis simulation studies for other things inclines me to think that people greatly overestimate how informative such small studies are once you allow for plausible levels of measurement error and (reverse) p-hacking degrees of freedom.
I would not believe that unless you have done a simulation study with the small n of this study, plausible levels of measurement error (alcoholism being much harder to measure than weight or body fat), with about a dozen covariates (to correspond to the different ways to slice the patients and threshold BMI etc), and then shown that you hardly ever get a false negative like this. My experience with doing such power analysis simulation studies for other things inclines me to think that people greatly overestimate how informative such small studies are once you allow for plausible levels of measurement error and (reverse) p-hacking degrees of freedom.