Applied physiology: The control of weight

SummaryOur understanding of the mechanisms involved in bodyweight regulation has increased enormously over the last 15 years. Unfortunately, the same time period has seen a trebling in the prevalence of childhood and adult obesity, the health consequences of which are enormous. While the cause for this increase undoubtedly lies in changes to our social environment, genetic factors strongly influence the response to these environmental changes. This article reviews current understanding of the systems controlling energy homeostasis, including the role of leptin and insulin as adiposity signals; neuropeptide Y and α-melanocyte-stimulating hormone as central mediators of the effects of these signals; and gut hormones such as ghrelin, which stimulates appetite, cholecystokinin, peptide YY 3–36, obestatin and oxyntomodulin in regulating meal size. It is hoped that our improving knowledge of the pathways regulating homeostasis and the dysregulation that occurs in obesity will lead to new, more effective treatments. The principal challenge, however, lies in changing the way we live so that obesity is not inevitable in a large proportion of the population.