This elevation in basal metabolic rate masks the effects of diet-induced thermogenesis mediated through β-adrenergic driven activation of BAT UCP1 compared to housing mice at thermoneutrality (TN, 29–30 °C) as evidenced by the development of obesity in mice lacking UCP1 at TN but not RT. This evidence concerns the gene UCP1 and obesity due to melanocortin 4 receptor deficiency.