LEP and obesity due to melanocortin 4 receptor deficiency: Given all these facts, not only leptin’s presence in milk should be considered as important, but also its possible daily changes throughout the day in milk, since the circadian or the daily oscillations in leptin and related molecules in different tissues and circulation may be linked to the pathogenesis of obesity and related disorders acting, among others, on brain and regulating satiety and feeding behaviour [23, 24].