EATING LESS AND GETTING FATTER

Abstract

Results from the most recent National Health and Nutrition Examination Survey indicate that over 65% of the US population are overweight. We realize that this is the unhealthy consequence of too much intake and too little physical activity. PURPOSE To test the hypothesis that much of the increase in the prevalence of overweight could be the consequence of decreased physical activity accompanied by insufficient decreases in energy intakes. METHODS A meta-analysis of peer-reviewed diet intake reports of healthy Americans with study dates 1930–1990. Over 100 articles were reviewed, and 47 of these had usable energy intake data for adolescent (12–19) or adult (20–50) Caucasian US males and females. Excluded were data from athletes, strenuous physical laborers, impoverished subjects, subjects with illnesses, or individuals on special diets. Only data from food recall and diet records were used. The final data set included average daily energy intakes from 12,078 adult females, 11,487 adult males, 4,483 adolescent females, and 4,381 adolescent males. Both weighted and unweighted regressions of mean caloric intake on study data were performed. RESULTS Among the first three groups we observed significant decreases in energy intake: adult females, p = 0.001; adult males, p = 0.02; adolescent females, p = 0.01. Although a decrease in energy intake was observed for the adolescent males, it did not reach significance, p = 0.14. The mean decrease in daily kilocalorie intakes and (percentage decreases) were: adult males: −640kcal (−20%); adult females: −325kcal (−16%); adolescent females: −460 kcal (−20%); and adolescent males: −340 kcal (−11%). CONCLUSIONS Results provide a qualitative estimate of the decrease in daily physical activity among these four US populations over the period 1930–1990.