Daily living is a rich source of inspiration for scientists specialising in weight management, and our interest in restaurants began with a simple problem—what to eat for lunch when trying to lose weight? Our research building at Tufts University has no cafeteria. There is yummy Chinese food just a block away, and one of us (SBR) was both partial to Chinese food and finding it hard to lose pregnancy weight. We measured the calories of some favorite meals using bomb calorimetry, which is the gold standard method for measuring food energy, and the horror of finding that a single takeout has more calories than needed for a whole day during weight loss led to a series of studies that continues today.
Our first protocols found that our Chinese takeouts were not unusual, and that most large chain restaurants in Boston serve meals containing far more calories than needed at a single meal. [1,2,3] We were also shocked to learn that low calorie menu items often contain more calories than stated—thus thwarting the best intentions of people, like us, ordering the sensible choices to manage their weight.  After that, it was a natural step to check whether restaurants across America overfeed their customers (yes, they do).  Our most recent study examined whether American restaurants are unusually bad on a global scale.  Our observation of meals in the different countries we visited for research meetings led us to suspect that restaurants were a problem everywhere, but the widespread lack of nutrition information meant that we had nothing to base our suspicion on except intuition.
Setting up an international restaurant study was a huge learning curve. We found that what is considered a “meal” is radically different across countries. The main meal of the day occurs at different times in different locations, and worksite canteens are a major aspect of daily life in some countries, but not others. There were also practical matters to tackle, such as how to ensure quality control across sites (answer: video instructions and multiple phone calls) and how to import food into the US (short answer: with enormous difficulty). With the exception of fast food in China, the results consistently told the same story—that all kinds of restaurants in all tested countries serve much more food than most humans need. Based on these results we believe that restaurants in general have got off too lightly in the search for valid intervention targets to reduce global obesity, and that it is time to redress the balance.
Of course, restaurants are not the only cause of weight gain, and an exclusive focus on restaurants without consideration of other factors will not make the world lean and healthy. That is why we’re also working to develop improved behavioral interventions for weight management based on the neurobiology of eating. [6-10] Our new approach is focused on making weight loss easier with effective management of hunger combined with behavioral support to make food preferences healthier. The results to date are promising, apparently yielding greater weight loss and control over food than traditional approaches without losing the enjoyment of good meals. [6,10] We have also created the International Weight Control Registry, to study the secrets of success of people in different countries around the world who have lost 5% or more of their starting weight. As we continue with our restaurant studies we will be using our intervention research and findings from the registry to identify successful approaches to weight control in different countries, and testing different versions in randomised trials. To date, no country has achieved success in reversing its obesity epidemic, but with continuing improvements in intervention science and progress in identifying effective intervention targets, including restaurants, we are optimistic that progress may now be possible.
Susan B Roberts is a professor of nutrition at Tufts University, and adjunct professor of psychiatry and scientific staff member in pediatrics at Tufts Medical School, Boston, USA.
Competing interests: SBR is the founder of the online iDiet weight loss programme (www.theidiet.com).
Sai Krupa Das is an associate professor of nutrition at Tufts University, Boston, USA.
1 Urban LE, Dallal GE, Robinson LM, Ausman LM, Saltzman E, Roberts SB. The accuracy of stated energy contents of reduced calorie, commercially prepared foods. J Am Diet Assoc. 2010 110:116-23.
2 Urban L, McCrory MA, Dallal GE, et al. Accuracy of stated energy contents of restaurant foods in a multi-site study. JAMA. 2011 306(3):287-93.
3 Urban LE, Lichtenstein AH, Gary CE, et al. The energy content of restaurant foods without stated calorie information. JAMA Internal Medicine 2013;173:11292-9.
4 Urban LE, Weber JL, Heyman MB, et al. Energy contents of frequently ordered restaurant meals and comparison with human energy requirements and US Department of Aagriculture database information: a multisite randomized study. J Acad Nutr Diet. 2016 Apr;116(4):590-8.
5 Roberts SB, Das SK, Suen VMM, et al. A multi-country study of the measured energy content of frequently purchased restaurant meals: a cross sectional survey. British Medical Journal 2018.
6 Salinardi TC, Batra P, Roberts SB, et al. A lifestyle intervention reduces body weight and improves cardiometabolic risk factors in worksites. Am J Clin Nutr. 2013 Apr;97(4):667-76.
7 Batra P, Das SK, Salinardi T, et al. Relationship of cravings with weight loss and hunger: results from a 6 month worksite weight loss intervention. Appetite 2013 Oct;69:1-7.
8 Batra P, Das SK, Salinardi T, et al. Eating behaviors as predictors of weight loss in a 6 month weight loss intervention. Obesity (Silver Spring). 2013 Nov; 21(11):2256-63.
9 Deckersbach T, Das SK, Urban LE, et al. Pilot randomized trial demonstrating reversal of obesity-related abnormalities in reward system responsivity to food cues with a behavioral intervention. Nutr Diabetes. 2014 Sep 1;4:e129
10 Das SK, Brown C, Urban LE, et al. Weight loss in videoconference and in-person iDiet weight loss programs in worksites and community groups. Obesity 2017;25(6):1033-41.