The prevalence of obesity has increased steadily over the past three decades. What was once primarily a problem for the industrialized Western nations is now a fully global phenomenon. The causes and possible solutions have been under debate for as long as the problem has existed. It involves synthesizing a wide range of scales from the metabolism of individuals to the global food supply. Recently, quantitative and mathematical methods have been applied. Accurate predictions of how much weight individuals will gain given their daily food consumption and physical activity can now be made using validated mathematical models of human metabolism. Models can also be used to dispel some myths about weight gain and weight loss. The dynamics at the individual level can be extended to the entire population of a nation. Applying such a calculation to the United States has shown that the increase in per capita food supply is more than sufficient to explain the obesity epidemic. In fact, per capita food waste has been progressively increasing simultaneously with obesity. These calculations have led to the push hypothesis for the obesity epidemic: dramatic increases in production, availability, and marketing of cheap, readily available food over the past few decades has led to increased food consumption and obesity along with increased food waste.This session describes how addressing the obesity epidemic requires an interdisciplinary and international team of researchers and practitioners.