Did the Food Environment Cause the Obesity Epidemic?

Abstract

Several putative explanations of the obesity epidemic relate to the changing food environment. Individual dietary macronutrients have each been theorized to be the prime culprit for population obesity, but these explanations are unlikely. Rather, obesity probably resulted from changes in the caloric quantity and quality of the food supply in concert with an industrialized food system that produced and marketed convenient, highly processed foods from cheap agricultural inputs. Such foods often contain high amounts of salt, sugar, fat, and flavor additives and are engineered to have supernormal appetitive properties driving increased consumption. Ubiquitous access to convenient and inexpensive food also changed normative eating behavior, with more people snacking, eating in restaurants, and spending less time preparing meals at home. While such changes in the food environment provide a likely explanation of the obesity epidemic, definitive scientific demonstration is hindered by the difficulty in experimentally isolating and manipulating important variables at the population level.

Figure 1

A) Macronutrient proportions of the US food supply as determined by the United Nations Food and Agriculture (FAO) food balance sheets (http://www.fao.org/faostat/en/#data/FBS). B) Total per capita energy content and contributions of carbohydrate, fat, and protein in the US food supply as determined by the FAO. C) Incremental increases in food energy supply since 1973 calculated using data from the FAO, United States Department of Agriculture (USDA) food availability (https://www.ers.usda.gov/data-products/food-availability-per-capita-data-system/food-availability-documentation/), and USDA loss-adjusted food availability (https://www.ers.usda.gov/data-products/food-availability-per-capita-data-system/loss-adjusted-food-availability-documentation/), along with calculated energy intake changes corresponding to the US population weight gain (12).