Harnack L J, Jeffery R W, Boutelle K N
Division of Epidemiology School of Public Health, University of Minnesota, Minneapolis, MN 55454-1015, USA.
Am J Clin Nutr. 2000 Jun;71(6):1478-84. doi: 10.1093/ajcn/71.6.1478.
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.
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.
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.
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.
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.
美国近期超重患病率上升的原因令人困惑，因为全国调查数据并未显示出能量摄入或消耗的明显变化模式。
回顾1970年至1998年间美国可获得的食物和营养素的数量及类型的生态学数据，以提供关于能量摄入趋势的另一种视角。
在农业、商业和医学图书馆数据库中进行文献检索，以确定1970年至1998年间美国可获得的食物和营养素的数量及类型的数据。
美国农业部《美国食品供应系列》中的人均能量可获得量估计表明，1970年至1994年间能量可获得量增加了15%。有关食品购买和制备趋势的数据表明，美国人在家庭以外用餐的次数增多，对方便食品的依赖程度更高，并且食物分量更大。在某些情况下，美国人似乎选择了低脂食物而非高脂食物。此外，低能量和低脂产品的可获得性及销售量有所增加。
与超重趋势一致，所回顾的大多数生态学数据表明，在过去几十年中能量摄入增加，这可能是平均体重增加的主要原因。
