ADRB2 and obesity due to melanocortin 4 receptor deficiency: These data, together with the results from animal studies showing that mice with betaadrenergic receptors knock-outs have reduced metabolic rate and developed massive obesity due to a failure of diet-induced thermogenesis [15] suggest that an unaffected function of ADRB2 and ADRB3 is crucial for thermogenesis and lipolysis in adipose tissue.