Body fat generally reflects long-term energy balance. In other words, it is a sign of how your eating habits (calories in) compare to your metabolic demand (calories out). It is not as simple as that though, as many people can attest after diligently carrying calorie tables about in a futile effort to match the numbers to the readout of a treadmill or recumbent bike. For decades, nutritionists and cardiologists extolled the virtues of low-fat dieting to reduce the risk of heart disease and aid in weight loss. On the surface, it made sense to replace the most calorie-dense macronutrient (fat) with carbohydrates, which contain less than half the number of calories, gram for gram. Yet, cardiovascular health was not greatly improved and the prevalence of obesity nearly tripled in the United States.

When dieting pioneers such as Barry Sears (the Zone Diet) and Dr. Robert Atkins (the Atkins Diet) suggested reducing carbohydrates dramatically and thusly adding fat back into the diet, the ideas were scoffed at by experts who staked their reputations on the risks and dangers inherent with such food practices. When the diet programs were newly released to the public’s attention, they were called “fads.” Over the next several months to years, as it was discovered that low-carbohydrate diets were effective for many people and became increasingly popular, the challenge of “no long-term studies” was pulled out of the critic’s handbook. Yet, as studies showed low-carbohydrate diets to be as effective, quicker and resulting in some cardiovascular benefits (not risks) when compared to low-fat diets, fickle America turned its attention-deficit addled focus to other issues. Doughnut sales began to recover from the Atkins-induced drop-off and crowds waited to form about the Alli stands at the local retailers. Even when a reasonable answer exists to a problem as personal and encompassing as obesity, America’s “been there, done that, bought the T-shirt” mentality has caused the nation to move on.