The catch-up fat phenomenon is an evolutionary conserved physiological response to a starvationrefeeding cycle. It is characterized by long-term suppression of thermogenesis, reduced body protein regain and an increase in fat mass above basal level during refeeding. Clinically, it characterises weight cycling in overweight patients which is associated with increasing fat mass (visceral fat) and increased morbidity (e.g. insulin resistance, inflammation). In this project, the physiological, cellular and molecular mechanisms of this phenomenon will be investigated in humans, mice and C. elegans. It is hypothesized that refeeding a low GI (=glycemic index)- diet after weight loss prevents the catchup fat phenomenon and its sequelae. This translational research will provide comprehensive insights into the catch-up fat phenomenon as well as provide a suitable strategy of its prevention.