The goal of this Theme is to improve physical and mental health across the lifecourse and to maximise healthy years lived. Our research spans key life-stages, from the early years through adolescence to old age, and it is carried out at different scales, from single cells to human populations. We use cutting-edge, high-precision methodologies in studies of selected neurones within the brain in order to better understand the mechanisms though which the body controls appetite, physical activity, energy expenditure, and body composition. We study the role of nutrition, physical activity, body composition, and the timing of food consumption (chrononutrition) in highly controlled conditions in our state-of-the-art Human Nutrition Unit. This work is complemented by our population-based research on the effect of inequalities and early life adversity in studies of over- and under-nutrition in large cohorts in the UK and in low-income countries.