The increasing global per capita energy intake, especially from refined carbohydrates and fats,11 as well as the positive association between rising rates of obesity and increasing energy intake across different countries,34 highlights the central role that overeating has played in the global obesity epidemic. However, identifying specific aspects of eating behavior, the food environment, or both that are quantitatively important and can lead to effective public health interventions has been challenging. To our knowledge, this is the first study of measured restaurant meal energy contents across different countries, allowing us to examine meals from full service and local fast food restaurants that do not routinely provide nutritional information. Notably, given the previous focus on high meal energy content as a particular problem in the US, only one country (China) had an average meal energy content that was significantly lower than the US value. In addition, substantial variability existed in meal energy content within countries, and in some cases more than a twofold difference existed in the energy content of the same meals purchased in different restaurants (for example, the same meal in China had 1386 and 657 kcal in restaurants 37 and 39 in supplementary table A), which would make providing consumers with guidance on how to eat less in restaurants extremely challenging in the absence of uniform menu labeling. Nevertheless, we observed some patterns—for example, single orders of popular meals ordered in fast food restaurants contained 33% less energy than meals in full service restaurants, in direct contrast to previous suggestions that the problem of excessive meal energy contents is specific to fast food. These results are broadly consistent with previous work by our team in the US in identifying restaurant meals in general, rather than fast food specifically, as an important target for interventions to reduce obesity,20212223 and they show that this is a global rather than a specifically US problem.

Implementing comparable protocols across six countries is challenging, and the study has several limitations. Firstly, despite the very large measured energy content of restaurant meals, this study almost certainly underestimates the restaurant meal orders made by consumers, because we analyzed only main course meals (entrées plus side dishes provided with them), whereas people dining out will typically order drinks, and sometimes appetizers and desserts, as well. In addition, although we collected the most popular orders as defined by the restaurants, we had no independent data on the frequency of meal purchases. Some restaurant patrons may also consume multiple meals at the same sitting, which would have resulted in further underestimation of meal energy. Seasonality was also not considered, and sampling was restricted to a specific urban area in each country. Concerning China specifically, because full service meals are consumed communally, the assumptions made in sample collection (an equal number of food items and diners on average) necessarily influenced the accuracy of projected meal energy levels. An additional general limitation was that most of the reference US data were collected about three years earlier than the data for other countries, but this is unlikely to have had a more than a small effect. We also assumed that the size of meals collected for taking away was the same as those supplied to diners inside the restaurants. These limitations notwithstanding, this study provides the first multinational data on measured energy contents of popular meals from full service and fast food restaurants and, as such, provides unique information relevant to the global obesity epidemic.

Interpretation and policy implications

Very high energy content of restaurant meals is problematic for several reasons. In particular, the frequency of consuming meals prepared away from home is increasing worldwide.35363738 In addition, even the average portion sizes measured in this study are very high relative to human energy requirements, especially for people with lower than average requirements such as sedentary people, older women, and people below average height. Our supplementary modeling data show that two average sized restaurant meals a day (one from a fast food restaurant and one in a full service restaurant) would provide almost all the daily energy requirement of a person with one standard deviation lower energy requirements than average, without any additional meals, drinks, snacks, appetizers, or desserts.

Large restaurant meals as measured here would not necessarily be a problem if people ate them infrequently, but, as noted above, dining out is now common. In addition, three meals and one or more snacks daily is usual worldwide, including in the countries studied here.39404142434445 Excessively sized restaurant meals may also normalize overeating in other situations,46 with a resulting further increase in energy intake. Although people eating out frequently may try to compensate by choosing smaller meals, the consistent associations between frequent eating out and body mass index suggest that this strategy is, at the very least, not fully effective.25262728 Part of the explanation for this phenomenon seems to be that humans have a poor ability to compensate for overeating at one meal by eating less at other meals, especially for higher energy meals and liquid calorie sources,47 resulting in a net increase in energy intake when eating of restaurant meals is frequent.2527 This may be due in part to the cephalic phase initiation of digestion, which is a normal physiologic mechanism whereby the sight and smell of food causes parasympathetic mediated preparations for digestion that include increased hunger, enlarged stomach lumen, and greater gastric motility.4849 Effectively, the human body is in equilibration with the immediate food environment via its cephalic phase, with the result that human eating patterns tend to synchronize with the available amount of food, whatever that amount is. Another innate mechanism that may contribute to overeating when portion sizes are very large is an increase in bite size without a compensatory decrease in the rate of bites, which results in a faster rate of energy ingestion.50

The results of this study support menu labeling for all restaurant foods, because in studies of large chain fast food restaurants, the introduction of labeling has been associated with reduced energy content of offered menu items over time,51 and the same benefit could potentially be achieved in all restaurants with uniform labeling requirements. We have previously provided an open access web tool to support recipe calculation by restaurants.52 In addition, our results suggest that recent public health recommendations to reduce restaurant meal servings to 600 kcal could become an important contributor to reducing the prevalence of obesity worldwide, by helping to prevent weight gain and providing active support for weight loss.33 Results of our supplementary modeling indicate that if restaurant meals were reduced to 600 kcals, even US adults with low energy requirements could consume up to seven restaurant meals a week without consuming more than 20% of daily requirements on average. However, 94% of meals from full service restaurants and 74% of meals from fast food restaurants contained more than 600 kcal in this study, indicating that substantial changes would be needed in all countries if the new guidelines were broadly adopted. We have also previously suggested that allowing restaurants to serve any meal size, as long as they additionally offer physiologically reasonable serving sizes of the same meals at a proportionally reduced price, could be a flexible option that would provide consumers with a strong economic incentive to reduce overeating when eating out.21 This option would also take into account the fact that many but not all people would benefit from meals as small as 600 kcal, allowing for larger orders to be placed by those who want a larger portion. Focus group studies have indicated that restaurant owners see ways to make proportional pricing mechanisms feasible, including by offsetting the lower profit margin on smaller portions by increasing the price of larger portions.53

During the past decade, substantial attention has been given to the potential role of fast food in the global spread of obesity, and public health interventions to reduce fast food consumption have been promoted.13 However, one intervention that reduced the availability of fast food with zoning regulations was associated with an increase in the prevalence of obesity rather than the reverse,17 and studies of the spatial association of obesity and fast food restaurants provide conflicting results.141516 Our study found that single servings of fast food meals contained less—not more—energy on average than full service meals (unweighted means: 809 v 1317 kcal/meal), and significantly lower values were also seen in three countries (Brazil, China, and US). It is also noteworthy that, although most large fast food chains did not meet the predefined criteria for restaurant density to be included in this study, local fast food restaurants are very common worldwide and have been shown to serve meals with energy contents that were broadly comparable.121854 Overall, the results of this study suggest that the controversy about the importance of fast food in the global obesity epidemic may be due to the fact that international fast food is only one of several types of meals prepared away from home that are served in excessive portion sizes. Our findings further suggest that new public health interventions should consider all types of meals prepared away from home as targets for intervention, not just meals from fast food restaurants providing nutritional information.

Two countries among the ones tested stand out as having potentially positive lessons for future interventions. Although, as noted above, there is greater uncertainty in the accuracy of the data from China than from the other countries in the study, China had 34% lower mean meal energy contents than the US (weighted means: 719 v 1088 kcal/meal) and the lowest mean fast food meal energy content of any country, which is likely to be a far greater difference than can be accounted for by the possible bias in sample collections. The number of countries tested was too small to analyze the relation of the energy content of restaurant meals with the prevalence of obesity, but nevertheless it is noteworthy that China has the lowest prevalence of obesity of any country in this study.1 Finland was another notable country because, although the energy contents of commercial full service and fast food restaurants were not different from US values, a finding consistent the high prevalence of obesity nationwide,55 the worksite canteen meals contained 25% less energy than full service and fast food restaurants (880 v 1166 kcal/meal). Worksite canteens in Finland are supported by social policies and included in dietary recommendations, and their widespread use has been linked to improved dietary habits.56

In contrast to the positive examples of China and Finland, Ghana and India had restaurant meal energy contents that were not different from the high values observed in the US, even though they are lower-middle income countries with limited financial resources for the treatment of diabetes, cardiovascular disease, and other non-communicable diseases resulting from obesity. Little information is available from these countries on the frequency of consumption of restaurant meals, but high meal energy content is likely to have a particularly negative impact, because smaller body sizes mean that restaurant meals are disproportionately large relative to energy requirements. As in the US, trends in these countries seem to be driven by a combination of consumer demand and the profits being made by food service industries,5758 indicating that government led interventions are more likely to be effective than voluntary industry sponsored changes.