I don't know how you define "properly" but the study did account for this, among many other factors:

"[...] We also investigated whether obesity, diabetes, and a healthy diet, all evaluated in 2 categories (no/yes), modified the association between LNCS consumption and cognitive decline by adding a 3-way interaction among the consumption of LNCS, the timescale, and each modifier on model 2."

In the results section: "[...] obesity and diet did not modify the association between LNCS consumption and cognitive decline [...]"