INS and obesity due to melanocortin 4 receptor deficiency: By inhibiting the expression of NF-κB, thereby improving insulin sensitivity and restoring the ratio of Firmicutes to Bacteroidetes in the intestine, Lactobacillus has now become a candidate probiotic for improving obesity and related diseases (such as hyperlipidemia and non-alcoholic fatty liver disease) (Wang et al., 2023; Lau et al., 2024).