For much of our history as a species, the threat of chronic food shortage and malnutrition has loomed over us. Fortunately, due to global economies and remarkable advances in technology and agriculture, most of the people reading this will never need to worry about starvation. But ironically, even as people in industrialized nations have largely overcome the problem of famine, we now must battle the consequences of excessive abundance of readily accessible food. All over the world, modern societies are confronting the challenge of obesity and diseases emanating from obesity. An analysis of trends in adult body mass published in the Lancet puts the progression of this public health crisis into useful historical perspective: It revealed that the number of obese individuals has risen from 105 million in 1975 all the way to 641 million as of 2016. Over the past 40 years, we have gone from a world in which prevalence of underweight was more than double that of obesity, to a worl