Meal types within each category are in the same order as those in Table 1, and statistical comparisons are described in Table 1. The dotted line represents one-third of the mean daily energy requirement for the average adult (667 kcal).21
Solid lines are means.
eTable. Measured gross energy content and portion weight in meals (entrees plus side dishes) and side dishes alone collected from independent and small-chain sit-down restaurants
Urban LE, Lichtenstein AH, Gary CE, Fierstein JL, Equi A, Kussmaul C, Dallal GE, Roberts SB. The Energy Content of Restaurant Foods Without Stated Calorie Information. JAMA Intern Med. 2013;173(14):1292-1299. doi:10.1001/jamainternmed.2013.6163
National recommendations for the prevention and treatment of obesity emphasize reducing energy intake through self-monitoring food consumption. However, little information is available on the energy content of foods offered by nonchain restaurants, which account for approximately 50% of restaurant locations in the United States.
To measure the energy content of foods from independent and small-chain restaurants that do not provide stated information on energy content.
We used bomb calorimetry to determine the dietary energy content of the 42 most frequently purchased meals from the 9 most common restaurant categories. Independent and small-chain restaurants were randomly selected, and 157 individual meals were analyzed.
Area within 15 miles of downtown Boston.
A random sample of independent and small-chain restaurants.
Main Outcomes and Measures
All meal categories provided excessive dietary energy. The mean energy content of individual meals was 1327 (95% CI, 1248-1406) kcal, equivalent to 66% of typical daily energy requirements. We found a significant effect of food category on meal energy (P ≤ .05), and 7.6% of meals provided more than 100% of typical daily energy requirements. Within-meal variability was large (average SD, 271 kcal), and we found no significant effect of restaurant establishment or size. In addition, meal energy content averaged 49% greater than those of popular meals from the largest national chain restaurants (P < .001) and in subset analyses contained 19% more energy than national food database information for directly equivalent items (P < .001).
Conclusions and Relevance
National chain restaurants have been criticized for offering meals with excess dietary energy. This study finds that independent and small-chain restaurants, which provide no nutrition information, also provide excessive dietary energy in amounts apparently greater than popular meals from chain restaurants or information in national food databases. A national requirement for accurate calorie labeling in all restaurants may discourage menus offering unhealthy portions and would allow consumers to make informed choices about ordering meals that promote weight gain and obesity.
Obesity and overweight remain at epidemic levels in the United States1 and are associated with substantial increases in the prevalence of comorbidities and health care costs.2- 4 National recommendations for the prevention and treatment of obesity emphasize individual self-monitoring of food consumption to reduce energy intake,5- 8 in part because energy intake is an essential contributor to energy balance and also because energy intake has risen by 217 to 491 kcal/d during the 40-year period when the prevalence of obesity has increased.2,9 However, self-monitoring of energy intake is substantially hampered by a lack of available information on the energy content of some quantitatively important food categories. In particular, almost no information is available on the energy contents of food purchased from restaurants that are not required to post nutrition information.
Restaurants are a major and increasing source of dietary energy, providing approximately 35% of daily energy intake in 2008.10 A recent report11 found that the stated energy content of restaurant foods providing nutritional information are broadly accurate, with the qualification that lower-calorie foods in sit-down restaurants have significantly more energy than stated and high-calorie foods have less energy than stated. However, although pending federal regulations will soon require restaurants with at least 20 outlets to post nutritional information at the point of purchase, only about 50% of restaurant locations in the United States are owned by companies with at least 20 outlets,12,13 and the other 50% are independent or small-chain establishments that will be exempt from the regulation. The lack of available nutritional information for foods purchased from a large segment of restaurants is further hampered by the very limited availability of national food database information for these meals that, if accurate, could substitute for restaurant-reported information.
We therefore conducted a study to measure the energy content of foods from independent and small-chain restaurants that do not provide stated information on energy contents. We acquired food samples from randomly selected restaurants to obtain information on the most popular food choices in the 9 most common restaurant types. We compared the information obtained with national dietary energy recommendations, the energy content of the most frequently purchased meals at national chain restaurants that provide nutrition information, and national food database information for directly equivalent meals.
We developed a random selection process to identify study foods, which were purchased from June 20 through August 22, 2011. The most common 9 categories of restaurants were defined as those with the greatest number of food outlets nationwide14: Mexican (n = 40 936), American (n = 37 230), Chinese (n = 28 914), Italian (n = 12 622), Japanese (n = 10 656), Thai (n = 4917), Indian (n = 2474), Greek (n = 2097), and Vietnamese (n = 1848). Restaurants potentially eligible for study were defined as all sit-down restaurants within 15 miles of downtown Boston that were accessible by public transportation and that provided an online menu but no nutrition information. Four restaurants in each cultural category were randomly selected; of the 4, 2 were selected from small restaurants (<10 employees) and 2 from large restaurants (≥10 employees). Random selection was conducted by assigning a number to each eligible restaurant, generating a random order of the numbers using commercially available statistical software (SAS, version 9.3; SAS Institute, Inc), and selecting the first 2 small and large restaurants within each cultural category. If a restaurant did not have the entire selection of targeted foods (see below), the next restaurant on the randomized list was selected.
Eligible meals for the study were the 5 most popular entree choices and standard accompanying side dishes because entrees and side dishes are the most frequently ordered menu items in sit-down restaurants.15 The specific items for study were identified according to customer rankings16 and from Internet searches for popular cultural food. The same 5 entrees were ordered from each restaurant within each cultural category. Dinner-sized portions of selected entrees were ordered as take-out meals from restaurants and were transported to the laboratory in the take-out containers supplied by the restaurants. The meals were refrigerated before analysis for energy content by bomb calorimetry.
Energy was determined using a validated bomb calorimetry method.17 Briefly, food samples were blended, freeze-dried, and ground into a homogeneous dry powder, and the heat of combustion was quantified in duplicate with benzoic acid as a standard for calibration. Duplicate simulated meals of 300, 900, and 1500 kcal were created specifically as standards to validate the method for this study. The same 4 basic foods with consistent nutrient contents as used in the previous validation17 (white wheat flour, granulated white sugar, corn oil, and nonfat dry instant milk) were combined in varying proportions to achieve macronutrient distributions of 20%, 10%, and 70% or of 30%, 30%, and 40% energy from fat, protein, and carbohydrates, respectively. Mean (SD) measured energy values were 4.1% (1.7%) less than values calculated from known compositions of the individual ingredients, which was slightly but significantly different from 0% (P < .001) and represented small energy losses during the transfer of the validation meals between different processing steps. Measured values were not adjusted for this offset. An adjustment of the raw data for this processing step would have increased rather than decreased the statistical significance of all results.
Gross energy content was the primary outcome. In addition to descriptive statistics, mean comparisons were made for total meals within and among cultural categories using analysis of variance with the Tukey post hoc test in a mixed model, with restaurant nested within restaurant category as a random factor. Comparisons of meal variability within and between categories were performed using the Levene test.18 Portion weight and restaurant size (small or large) were added to the mixed model in post hoc testing, and univariate linear mixed regression models within each category were subsequently fit. For Asian foods, rice was considered part of the entree.
Next, comparisons were made between foods measured in this study and the most popular foods ordered from national chain restaurants that provide nutrition information with an independent t test and, for matched entrees, a paired t test. Measured gross energy values from previous studies11,17 were used for national chain restaurant foods when available (10 entrees [13%], 41 side dishes [58%]). Otherwise, metabolizable energy values (energy available to the body after obligatory losses in feces and urine) stated on the chain restaurant websites were converted to gross energy equivalents using stated macronutrients and standard Atwater factors19 in the following equation:
Gross Energy = (Fat × 9.4) + (Protein × 5.65) + (Total Carbohydrates × 4.15),
where gross energy is given in kilocalories and fat, protein, and carbohydrates are all measured in grams. Significant differences between measured and stated energy contents of restaurant foods have been shown to depend on the magnitude of the stated energy17; therefore, this equation may underestimate or overestimate gross energy for individual foods.
Finally, although the latest US Department of Agriculture Nutrient Database for Standard Release, version 24 (SR-24)20 contains very few data from independently measured restaurant meals, some data do exist. Therefore, in post hoc analyses, we identified meal information in the SR-24 with an exact name match to meals analyzed in this study and compared the data using a paired t test. We used standard Atwater factors as above to revert the SR-24 energy values to standard gross energy values. We then compared gross energy values for foods in the SR-24 with gross energy of the same foods measured in the present study.
All statistical analyses were performed by using the same statistical software (SAS for Windows, version 9.3; SAS Institute, Inc). When data were skewed, energy was transformed before analysis.
A total of 180 meals were planned for this study. Only 3 of the intended 4 Vietnamese restaurants found in the study area were eligible. Pizza meals were retrospectively excluded from the American category because of the inability to determine what should constitute a serving size. One Japanese meal from 1 restaurant was eliminated as a result of a processing error, and 2 Japanese sushi meal types were retrospectively excluded as too small to constitute whole meals. Finally, 1 Italian restaurant was later excluded when it was discovered to be part of a national chain. Thus, a total of 157 meals were included in the data analyses representing all 9 restaurant categories and 42 meal types. Mean meal energy content, portion weight, and energy density are listed in Table 1 by category, and individual data, including side dishes, are available in the eTable in Supplement. Meals contained a mean of 1327 (95% CI, 1248-1406) kcal. The energy contents of American, Chinese, Indian, and Italian meals were greater than the mean, whereas Mexican, Greek, Thai, Vietnamese, and Japanese meals were less than the mean. Among categories, Vietnamese meals had significantly less energy than American, Chinese, Indian, and Italian meals (P ≤ .05 for all), and Italian meals had significantly more energy than Japanese, Thai, and Greek meals (P ≤ .05 for all). Variability for the average within-meal SD was generally high at 271 (range, 51-916) kcal. We also found differences in variability between meal types; specifically, American meals (average SD, 808 kcal) were more variable than Thai (303 kcal), Indian (411 kcal), and Greek (308 kcal) meals (P ≤ .04 for all). The mean energy content of the meals was twice the amount required for weight maintenance (Figure 1), conservatively assuming that each daily meal should contain one-third of the daily energy requirement, which is set at 2000 kcal/d by the US Food and Drug Administration for typical daily energy requirements in all nutrition labeling.21 Furthermore, 75.2% of individual meals contained at least 50% of the daily energy requirement, and 7.6% contained 100% or more.
Regression analyses examined factors other than restaurant category that might also determine the energy content of the meals (Table 2). The size (number of employees) of the restaurant was not predictive of meal energy (P = .88), and the covariance factor for the random effect of restaurants was estimated as 0 after accounting for other predictors, indicating no influence on energy content. However, we found a statistically significant portion weight (in grams) by category interaction (P < .001). Portion weight was positively associated with meal energy for Mexican (P = .003), American (P < .001), Indian (P < .001), and Greek (P < .001) meals. The effect of portion weight on energy content was greatest in American meals: a 100-g increase in portion weight predicted a 320-kcal increase in meal energy content.
Energy values obtained in this study were compared with energy values for comparable named entrees from national chain sit-down restaurants that provided energy information and for the most popular (nonmatched) entrees from the overall largest national chain restaurants (Figure 2).22 This comparison reflects the different choices that people make when eating in different types of restaurants, thereby justifying the comparison of the data obtained herein with the most popular nonmatched meals from chain restaurants. For the matched comparison, we identified 44 entrees available at 12 sit-down national chain restaurants in the top 400 for overall sales that matched the entree names in the present study and had nutrition information available. In a paired analysis, the entrees in this study had 18% more energy than the same entrees in chain restaurants (1223 vs 1041 kcal; P = .11); when free side dishes were included in the comparison, the difference was only 6% (1437 vs 1359 kcal; P = .79), indicating that different types of restaurants provide similar levels of overall calories but different proportions of entrees and side dishes. For the nonmatched comparison of data obtained in this study with the overall most popular national chain restaurant meals, we identified 36 meals from the 9 most popular chain restaurants in the United States (7 quick-serve and 2 sit-down restaurants). The meals in this study contained significantly more energy when the comparison was performed for entrees alone (+108%, at 1166 vs 559 kcal [P < .001]) and when the comparison was performed for entrees plus side dishes (+49%, at 1327 vs 890 kcal [P < .001]).
The SR-24 has relatively few independently measured nutrient values for restaurant foods and included information for close matches to only 4 of the meal choices in this study, all of them from the Chinese food category (Table 3). Nevertheless, the measured meals contained 19% more energy than the matching database values (P < .001), were similar in energy density (in kilocalories per gram [P = .91]), and tended to have greater portion weights (P = .06).
Large national chain restaurants have been criticized for contributing to the obesity epidemic by providing meals with excess dietary energy.23- 26 This study demonstrates that independent and small-chain restaurants, which make up approximately 50% of national restaurant outlets12,13 but provide no nutrition information, may be equally important contributors because their most popular food choices provide twice as much energy as required for weight maintenance. We also found evidence indicating that these independent and small-chain restaurants may provide more energy than the most popular meal choices in national chain restaurants and that their energy contents are underestimated in the limited information available in the national food database. In view of the observation that restaurants improve the nutritional profiles of their meals when required to report information,27,28 much more widespread reporting of meal energy contents is warranted.
We identified the most popular food items from the most popular cultural restaurant types nationally, and we analyzed a total of 157 orders representing 42 different types of meals. Meals contained a mean of 1327 kcal, which, using conservative assumptions, is twice the estimated dietary energy needs of an individual adult at a single meal (one-third of the national daily calorie target of 2000 kcal/d specified by the US Food and Drug Administration),21 and 7.6% of meals contained more than the whole daily energy requirement. In addition, this study focused on entrees and side dishes and did not include the appetizers, desserts, and drinks that are commonly included in meals. With the exception of Vietnamese meals, which were significantly lower in energy content than many other cuisines, we found no significant difference in the energy content of different cultural cuisines but substantial variability in the energy content within and between meal types. For example, an order of ribs in American restaurants contained from 1511 to 3381 kcal, and an order of tandoori chicken in Indian restaurants contained from 1192 to 2921 kcal. This high variability was only partly due to variations in the portion sizes of the meals and, when considered with the fact that nearly all meals contained more dietary energy than that required for weight maintenance, meant that we could not use the study data to develop general recommendations for cuisines or specific meals that would facilitate weight maintenance rather than promote weight gain.
Another noteworthy finding in the study was that the energy content of the measured meals was a surprising 49% higher than the energy content of the most popular meals from the most popular restaurants nationwide, and the entrees alone also contained 18% more energy than directly equivalent dishes from larger chain restaurants that provided stated nutrition information. Given that an imbalance between energy intake and energy expenditure of only 100 kcal/d is predicted to cause a weight gain of 2.6 to 7.0 kg/y,29- 31 the excessively high energy content of individual courses from individual and small chain restaurants may play an important role in the national obesity epidemic, especially when consumers are unable to make an informed selection of items because no information on dietary energy content is provided.
The need for more information on the nutrition content of restaurant meals is partially addressed by pending federal legislation that will soon require restaurants to provide information.32 However, only restaurants with at least 20 outlets are subject to the ruling, and individual and smaller-chain restaurants such as those investigated in this study will be exempt even though they make up approximately 50% of restaurant establishments in the United States. Although there is controversy over whether nutrition information reliably alters consumer choices,33- 37 the requirement to report high energy content appears to encourage restaurants to reduce the energy content of their meals.27,28 In relation to this observation, calculating the nutrient content of different meals would be a relatively small task for restaurant owners because cost-free software is widely available for this purpose. As an alternative to more restaurant menu labeling, consumers could use information obtained in this study and be responsible for eating less. However, studies on portion size and food consumption consistently report that provision of larger servings leads to increased energy intake during the meal and over the course of several days.38- 40 There are perceptual reasons for why this phenomenon occurs. For example, Wansink and Chandon41 reported that, although consumers estimate the energy content of small (about 500 kcal) restaurant meals fairly accurately, they underestimate energy intake with large portions; for the typical portion size found in this study, the underestimation would be a sizable 30%.
Another notable finding in this study was the lack of independent information on the energy content of the most popular national restaurant meals in the national SR-24 nutrient database. Moreover, the limited information available for popular restaurant meals significantly underestimated measured meal energy content by an average of 19% (based on available data, for Chinese food only); therefore, persons using this database to estimate their daily energy may inadvertently consume more calories than they intend. Because of the considerable number of foods available in the United States and the large number of new products introduced annually, expectations that the national databases will be fully updated annually are not realistic. However, in view of the fact that independent and small-chain restaurants are so prevalent, much greater emphasis on providing nutrition information for their most popular foods is needed.
In summary, meals from independent and small-chain restaurants that do not provide nutrition information contain a mean of twice as much energy as required for weight maintenance, more energy than the most popular meal choices from the largest national chain restaurants that provide nutrition information, and more energy than that recorded in a national food database for the specific named foods. We recommend routine reporting of meal energy content by all restaurants, not just national chains, to discourage restaurants from offering unhealthy portions. This reporting would also allow consumers to make informed choices about their diet.
Corresponding Author: Susan B. Roberts, PhD, Energy Metabolism Laboratory, Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, 711 Washington St, Boston, MA 02111 (email@example.com).
Accepted for Publication: December 4, 2012.
Published Online: May 13, 2013. doi:10.1001/jamainternmed.2013.6163
Author Contributions: Dr Roberts had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Urban, Lichtenstein, Gary, Fierstein, and Roberts.
Acquisition of data: Urban, Gary, Fierstein, Equi, and Kussmaul.
Analysis and interpretation of data: Urban, Lichtenstein, Equi, Dallal, and Roberts.
Drafting of the manuscript: Urban, Lichtenstein, Gary, Fierstein, and Roberts.
Critical revision of the manuscript for important intellectual content: Urban, Lichtenstein, Gary, Fierstein, Equi, Kussmaul, Dallal, and Roberts.
Statistical analysis: Urban, Equi, and Dallal.
Obtained funding: Lichtenstein and Roberts.
Administrative, technical, and material support: Urban, Lichtenstein, Gary, Fierstein, Equi, Kussmaul, and Roberts.
Study supervision: Urban, Lichtenstein, and Roberts.
Conflict of Interest Disclosures: None reported.
Funding/Support: This study was supported by the US Department of Agriculture under agreements 58-1950-0-0014 and 1950-51000-072-02S with Tufts University.
Disclaimer: Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the US Department of Agriculture.
Additional Contributions: Tyler Lewtan (a high school intern at the Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging) helped with bomb calorimetry and data entry and received no compensation.