FTO and obesity due to melanocortin 4 receptor deficiency: Enrichment of A. muciniphila leads to generate more indole‐3‐lactic acid (ILA) to upregulate the expression of 12α‐hydroxylase (CYP8B1) via fat mass and obesity‐associated protein (FTO)/ N6‐methyladenosine (m6A)/YTHDF2 manner, thereby facilitating cholesterol converts to cholic acid (CA).