FFAR4 and obesity due to melanocortin 4 receptor deficiency: Considering that FFAR4 is implicated in various pathological and physiological processes, including inflammation, the secretion of glucagon-like peptide-1, adipocyte differentiation, insulin sensitization, the regulation of appetite, and tumor progression, FFAR4 represents a promising target not only for osteoporosis, but also for the treatment of obesity-related metabolic disorders, such as cancer.