From 1977 to 1996, the average person 2 years old increased restaurant/fast food consumption from 9.6% to 23.5%.7 During this time period,young adults age 18 to 39 have had the greatest increase in restaurant and fast food consumption. Restaurant and fast food consumption now represents 32% of the total calories ingested per person, or one-third of daily total energy. The amount of calories consumed per eating occasion is greater from food prepared away from
home as compared with food prepared at home. Eating restaurant or fast food increases energy intake, and people who consume this food have a significantly higher odds of being overweight compared with those who do not eat fast food (odds ratio, 1.27 and 1.31, respectively).8 There is a positive association between the frequency of eating restaurant or fast food and increases in body weight. Pereira et al9 found that over a 5-year period, eating fast food 3 times per week is associated with 1.6 kg to 2.2 kg weight increase (P .01). Furthermore, analysis of state-level data indicates that the number of residents in a region per fast food restaurant correlates with the prevalence of obesity (r 0.53; P .001). Thus, multiple lines of evidence indicate that frequency of eating restaurant or fast food is associated with positive energy
balance and excessive weight. The studies above do not distinguish between restaurant food and fast food. Duffey et al11 find this to be a limitation in previous studies of this behavior. Their findings from a longitudinal study indicate significant increases in BMI with fast food consumption over time, but not with restaurant food consumption. Duffey et al found a 0.13-unit increase in BMI at 7 years with each unit (1 time/wk) increase in fast food consumption (P .003),
and this increase in BMI was sustained at 10 years (P .001). Conversely, longitudinal increases in restaurant food consumption resulted in minimal, but not significant, decreases in BMI (P .756 at 7 years, P .676 at 10 years).11
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