INS and obesity due to melanocortin 4 receptor deficiency: In 2019, Patrice D. Cani’s team, based on previous animal studies, published the results of the first clinical trial of A. muciniphila, which demonstrated that supplementation with inactivated A. muciniphila significantly improved several metabolic indices in people with overweight or obesity and insulin resistance, triggering a discussion on the concept of “postbiotic” and its potential application (Depommier et al., 2019).