I follow scientist Gid M-K on Medium for his detailed explanations of what new research actually means. In this (unlocked) article he discusses research relating obesity and environmental obesogens.
One of the researchers’ recommendations includes not wearing your shoes inside in order to minimize tracking in pesticide residue. Gid’s conclusion is that not only is this recommendation wildly speculative and currently unsupported by the research itself, but that the press has misreported the findings.
So, don’t worry – wearing your shoes inside isn’t causing you to gain weight.