Background: The causes of recent increases in the prevalence of overweight in the United States are perplexing because national survey data do not show clear patterns of change in energy intake or expenditure.
Objective: Ecologic data regarding the quantities and types of foods and nutrients available in the United States between 1970 and 1998 were reviewed to provide an alternative perspective on trends in energy intake.
Design: Literature searches in agriculture, business, and medical library databases were conducted to identify data regarding the quantities and types of foods and nutrients available in the United States between 1970 and 1998.
Results: Per capita energy availability estimates from the US Department of Agriculture, US Food Supply Series, indicate that energy availability increased by 15% between 1970 and 1994. Data regarding trends in food purchasing and preparation suggest that Americans are eating more meals outside the home, relying more heavily on convenience foods, and consuming larger food portions. Americans appear, in some cases, to be selecting lower-fat foods over higher-fat alternatives. In addition, availability and sales of reduced-energy and reduced-fat products have increased.
Conclusion: Consistent with trends in overweight, most of the ecologic data reviewed suggest that energy intake has increased over the past several decades and is likely a major contributor to increases in average body weight.