Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-5621, USA.
Thermostats have "set-points" that engineers design with mathematical rigor. Work in this issue of Cell Metabolism (Tam et al., 2009) applies similar modeling strategies to explore the control of murine energy and body weight homeostasis by leptin.