McCRORY, MEGAN A., PAUL J. FUSS, NICHOLAS P. HAYS, ANGELA G. VINKEN, ANDREW S. GREENBERG, AND SUSAN B. ROBERTS. Overeating in America: association between restaurant food consumption and body fatness in healthy adult men and women ages 19 to 80. Obes Res . Purpose : To examine the association between the frequency of consuming restaurant food and body fatness in adults. Research Methods and Procedures : Usual free‐living dietary intake and the frequency of consuming food from seven different restaurant types (fried chicken, burger, pizza, Chinese, Mexican, fried fish, and “other”) were assessed by food frequency questionnaire in 73 healthy men and women [ages 19 to 80, body mass index (BMI) 18 to 331. In addition, body fatness (percent weight) was determined by hydrostatic weighing, and physical activity and other lifestyle parameters were assessed by questionnaire. The relationship between the frequency of consuming restaurant food and body fatness was determined after controlling for age, sex, and other confounders by using multiple regression techniques. Results : Restaurant food consumption averaged 7.5±8.5 (Standard Deviation) timedmonth. After controlling for age and sex, the frequency of consuming restaurant food was positively associated with body fatness (partial r = 0. 36, p = 0. 003). The strength of this association did not change after controlling for education level, smoking status, and alcohol intake, but after additionally controlling for physical activity, the partial r increased to 0. 42 ( p = 0. 004). Total daily intakes of energy, fat, and fiber were significantly associated with restaurant food consumption frequency (r = 0. 59, 0. 28, and −0.45, respectively, p = 0.02 to 0.0001). Discussion : The frequency of consuming restaurant food was positively associated with increased body fatness in adults. The increasing proportion of household food income spent on food prepared away from home in the United States may therefore help explain the rising national prevalence of obesity.