The easy availability of large portions of relatively energy-dense foods may contribute to the increasing prevalence of obesity in the U.S.
An article published in the American Journal of Clinical Nutrition explained the effects of portion size on overall food intake.
Researchers concluded that large food portions typically served in American restaurants or self-service during family meals significantly affect the risk of obesity.
The 51 men and women who participated in the study, aged 21-40 years, were not trying to either gain or lose weight. They initially completed 4 questionnaires to determine whether they usually exercised self-restraint in the presence of large portions of food.
Participants were provided a test lunch that included a macaroni and cheese entrée. Twenty-seven participants received the entrée on individual plates in varying portions from small to large; the other 24 subjects served themselves as many helpings as they desired.
Five members of each group were identified as "plate cleaners" who consumed the entire portion of each serving. Both men and women ate more in response to a larger portion size, though females overall consumed an average of 30 percent less food than males.
Less than one half of the men and women reported noticing any difference in the portion sizes they were served at meals.
The authors suggested that people have expect the amount of food served to them by others is appropriate. They advised that strategies to limit portion sizes in restaurants or at home should be developed in order to stem the national obesity epidemic.
Source: Rolls, Barbara J et al. Portion size of food affects energy intake in normal-weight and overweight men and women. Am J Clin Nutr 2002;76:1207-13. <http://www.faseb.org/ajcn/Dec2002/13513.Rolls.PDF>
