Stated calories on menus of certain restaurants appear to be accurate overall

"The prevalence of obesity in the United States increased from 14 percent of the population in 1976 to 34 percent in 2008, during which time both self-reported and per-capita energy intake increased. Reducing energy intake by self-monitoring or selecting foods with lower energy contents is widely recommended for the prevention and treatment of obesity. However, the feasibility of reducing energy intake using these approaches depends in part on the availability of accurate information on the energy contents of different foods," according to background information in the article. "Foods purchased in restaurants provide approximately 35 percent of the daily energy intake in U.S. individuals but the accuracy of the energy contents listed for these foods is unknown."

Lorien E. Urban, Ph.D., of Tufts University, Boston, and colleagues conducted a study to evaluate the overall accuracy of restaurant-stated energy contents and examine factors associated with the accuracy of stated energy contents of individual food items. Food from 42 restaurants, comprising 269 total food items and 242 unique foods, were ordered as a take-out meal and subsequently analyzed at a laboratory for caloric content. The restaurants and foods were randomly selected from quick-serve and sit-down restaurants in Massachusetts, Arkansas, and Indiana between January and June 2010.

Of the 269 food items, 108 (40 percent) had measured energy contents at least 10 kcal (calories)/portion higher than the stated energy contents and 141 (52 percent) had measured energy contents at least 10 kcal/portion lower than the stated energy contents. Nineteen percent of foods contained greater than 100 kcal/portion more than the stated energy contents. The researchers found significantly greater variability in the discrepancy between the stated and measured energy contents in all foods from sit-down restaurants compared with all foods from quick-serve restaurants.

In an analysis of 10 percent of foods (n= 17) from both quick-serve and sit-down restaurants with the highest positive discrepancy between measured and stated energy contents, these foods had an average difference between measured and stated energy contents of 289 kcal/portion, and there was a similar discrepancy in a subsequent re-analysis of 13 of these foods (258 kcal/portion). "Considering the first and second sampling of the 13 foods together, the 26 foods had a mean [average] measured energy content of 273 kcal/portion higher than the stated energy content, representing a 48 percent discrepancy," the authors write.

"In addition, foods with lower stated energy contents contained higher measured energy contents than stated, while foods with higher stated energy contents contained lower measured energy contents."

The authors suggest that a reason why individual foods have inaccurate stated energy contents (especially in sit-down restaurants) may be poor quality control of portion size.

"The results of this study have implications for pending implementation of new legislation requiring more restaurants to document the energy content of their menu items," they write. "Although our study showed that stated energy contents in restaurants are relatively accurate on average, thus supporting greater availability of this information, projected benefits for preventing weight gain and facilitating weight loss are likely to be reduced if restaurant foods with lower stated energy contents provide more energy content than stated. Additional portion control in restaurants has the potential to facilitate individual efforts to reduce energy intake and to help resolve the national obesity epidemic."

Editorial: Calories Count -- But Can Consumers Count on Them?

The value of the law regarding labeling of caloric content can be enhanced considerably through effective public health education campaigns to facilitate its use, writes Linda Van Horn, Ph.D., R.D., of the Northwestern University Feinberg School of Medicine, Chicago, in an accompanying editorial.

"Primary prevention efforts could be markedly improved through better parental awareness of the caloric needs of their children and, ideally, the capacity to role model their own energy balance. Limited data document that adult consumers are often unable to estimate caloric differences across unlabeled food items; however, among those who read posted caloric contents, reduced caloric intake occurs. Prevention and treatment of overweight and obesity require change in the environment as well as in personal behavior."

"Just as balancing a budget can prevent debt, balancing caloric intake with output can prevent added pounds. However, U.S. residents seem to be struggling with both balancing acts. New, innovative, and effective approaches to teaching about energy balance and caloric control are greatly needed."