Tannerella forsythia and coating color on the tongue dorsum, and fatty food liking associate with fat accumulation and insulin resistance in adult catch-up fat

Background/Objectives: We aimed to determine the alteration of Tannerella forsythia and coating color on the dorsal tongue, and fatty food liking in catch-up fat in adult (CUFA), as well as the probable associations between fat accumulation, insulin resistance (IR) and these changes. Subjects/Methods: T. forsythia on the tongue dorsum, fatty food liking, fat accumulation and insulin sensitivity were investigated in CUFA humans and rats, and tongue-coating color was observed in CUFA individuals. We further determined the changes of fatty food liking, fat accumulation and IR in T. forsythia -infected rodents by oral lavage. Results: Increases in fat accumulation, IR, percentage of subjects with yellow tongue coating and that with T. forsythia detected were observed in CUFA individuals. Additionally, the fat ranking scores were significantly lower and the hedonic ratings of low-fat options of sampled food were lower, while the ratings of high-fat options were remarkably higher in CUFA subjects. Additionally, T. forsythia level elevated in CUFA rats, and fatty food liking, fat accumulation and IR increased in CUFA and T. forsythia -infected animals, with the increases in T. forsythia infection and fatty food liking preceding the occurrence of fat accumulation and IR. Conclusions: T. forsythia and yellow coating on the dorsal tongue and fatty food liking associate fat accumulation and IR in CUFA. Moreover, we tentatively put forward that T. forsythia , which is very important in yellow tongue-coating microbiota, and its consequent increases in fatty food liking, might be crucial in the development of fat accumulation and IR in CUFA.