Accuracy of Stated Energy Contents of Restaurant Foods
Are reported calorie counts for restaurant food accurate?
A total of 269 food items and 242 unique foods were measured for dietary energy using a validated bomb calorimetry technique. Foods were chosen from 42 restaurants. Both foods and restaurants were randomly selected from quick-serve and sit-down restaurants in Massachusetts, Arkansas, and Indiana between January and June 2010. The primary outcome of interest was the difference between restaurant-stated and laboratory measured energy contents, which were corrected for standard metabolizable energy conversion factors.
Overall, the stated energy contents were not significantly different from the measured energy contents (p = 0.52). However, of the 269 food items, 50 (19%) contained measured energy contents of at least 100 kcal/portion more than the stated energy contents. Of the 10% of foods with the highest excess energy in the initial sampling, 13 of 17 were available for a second sampling. In the first analysis, these foods contained average measured energy contents of 289 kcal/portion (95% confidence interval [CI], 186-392 kcal/portion) more than the stated energy contents; in the second analysis, these foods contained average measured energy contents of 258 kcal/portion (95% CI, 154-361 kcal/portion) more than the stated energy contents (p < 0.001 for each vs. 0 kcal/portion difference). In addition, foods with lower stated energy contents contained higher measured energy content than stated, while foods with higher stated energy contents contained lower measured energy contents. Side dishes from sit-down restaurants contained higher measured energy contents than stated compared with the entrees they accompanied, and were significantly more variable relative to measured energy content.
The investigators concluded that stated energy contents of restaurant foods were accurate overall. However, there was substantial inaccuracy for some individual foods, with understated energy contents for those with lower energy contents.
This study provides valuable information on food consumed outside of the home. Since many Americans frequently eat meals outside the home, information on variability of caloric content reported versus actual calories has important implications for those attempting to lose weight.
Keywords: Meals, Calorimetry, Body Weight, Energy Intake, Restaurants, Indiana, Massachusetts, United States
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