title: Temporal trends in energy intake in the United States: an ecologic perspective.
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Epidemiology School of Public Health, University of Minnesota, Minneapolis, MN 55454-1015, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Harnack
authors.forename: R W
authors.initials: RW
authors.lastname: Jeffery
authors.forename: K N
authors.initials: KN
authors.lastname: Boutelle
mesh_terms: D003258:Consumer Behavior; D018752:Diet, Fat-Restricted; D004041:Dietary Fats / Q000008:administration & dosage; D004463:Ecology; D002149:Energy Intake; D004734:Energy Metabolism; D005247:Feeding Behavior; D005518:Food Preferences; D006801:Humans; D016239:MEDLINE; D009747:Nutritional Physiological Phenomena; D009765:Obesity / Q000453:epidemiology; D014481:United States
chemical_list: D004041:Dietary Fats