Weight in the balance.

The adage 'we are what we eat' is taking on a new meaning in our well-fed and increasingly sedentary culture, as many of us convert much of our excess food into body fat; in the USA, 60% of the population is now considered to be overweight. Obesity brings with it an increased risk of developing type II diabetes, hypertension and heart disease, so the mechanisms that control food intake and body weight are of considerable importance for public health and clinical medicine. The mass of body fat is now known to be regulated by several hormones and neuropeptides. Two of these, the circulating peptide hormones leptin and ghrelin have actions that include reciprocal effects on appetite-regulating neurons in the hypothalamus. This article reviews data discussed at a recent meeting(1), where an overview of recent developments in research into leptin and ghrelin was presented. Topics covered are the roles of leptin and ghrelin in the regulation of food intake and energy production; the integration of food intake with other energy-regulated processes, such as growth, sexual maturation and reproduction, sleep and the immune response; and pathological conditions, ranging from diabetes to psychiatric disorders.1 This report summarizes conclusions of the meeting 'Brain Somatic Cross-Talk and the Central Metabolism' held in Paris on January 28, 2002.