FTO and obesity due to melanocortin 4 receptor deficiency: Many obesity-related genes are expressed or are known to act in the central nervous system, especially in the hypothalamus, and the association between the expression of these genes and BMI may explain increases or decreases in appetite, such as via regulation of the feeding center in the hypothalamus.38,41 However, even after adjusting for total energy intake, FTO loci remained significantly associated with current BMI and BMI change.