Chapter 1 traces the origins and evolution of the obesity epidemic. Combating obesity requires understanding its root causes. Conventional wisdom holds that consuming too many calories and exercising too little leads to weight gain. This belief gave rise to the maxim “Eat Less, Move More.” Fung problematizes this approach to obesity by distinguishing between the proximate and ultimate causes of weight gain. Eating too much may be immediately responsible for weight gain (the proximal cause), but it is not what starts the chain of events (the ultimate cause). Moreover, obesity is not a personal failing or choice, as the maxim implies. Women have almost 50% more body fat than men, even though men generally consume more calories (12). Women are not lazier than men, nor do they lack self-control. Rather, hormones make it more difficult for women to burn calories. Despite the clear problems with the “Eat Less, Move More” strategy, government organizations continue to promote it as the gold standard for weight loss.

Starting in the late 18th century, health experts posited a link between weight gain and carbohydrates (sugar molecules found in sugary and starchy foods). The increased prevalence of coronary disease in the mid-20th-century (largely attributable to longer lifespans) led to the replacement of dietary fats with other food types, namely, carbohydrates.