International Journal of Obesity (2015) 39, 542–545 © 2015 Macmillan Publishers Limited All rights reserved 0307-0565/15 www.nature.com/ijo
SHORT COMMUNICATION
Calorie-labelling: does it impact on calorie purchase in catering outlets and the views of young adults? CK Nikolaou, CR Hankey and MEJ Lean Calorie-labelling of meals has been suggested as an antiobesity measure, but evidence for impact is scarce. It might have a particular value for young adults, when weight gain is most rapid. A systematic literature review and a meta-analysis was performed to assess the effect of calorie-labelling on calories purchased. Seven studies met the inclusion and quality criteria of which six provided data allowing a meta-analysis. Three reported significant changes, all reductions in calories purchased (−38.1 to − 12.4 kcal). Meta-analysis showed no overall effect, − 5.8 kcal (95% confidence interval (CI) = − 19.4 to 7.8 kcal) but a reduction of − 124.5 kcal (95% CI = − 150.7 to 113.8 kcal) among those who noticed the calorie-labelling (30–60% of customers). A questionnaire, to gauge views on calorie-labelling, was devised and sent to young adults in higher education: 1440 young adults (mean age 20.3 (s.d. = 2.9) years) completed the survey. Nearly half (46%) said they would welcome calorie information in catering settings and on alcoholic drinks. Females opposing to calorie-labelling were heavier to those who did not (64.3 kg vs 61.9 kg, P = 0.03; BMI = 22.4 kg m−2 vs 21.7 kg m−2, P = 0.02). In conclusion, the limited evidence supports a valuable effect from clearly visible calorie-labelling for obesity prevention, and it appears an attractive strategy to many young adults. International Journal of Obesity (2015) 39, 542–545; doi:10.1038/ijo.2014.162 INTRODUCTION The prevalence of obesity has been increasing worldwide along with a profusion of catering outlets (locations providing out-ofhome meals, including fast-food restaurants, chain restaurants and independent restaurants) and corresponding increases in the numbers of meals eaten outside home.1 Calorie-labelling has been proposed as an antiobesity measure by providing a tool to inform consumers and help them manage their overall calorie intakes. Calorie-labelling was included as a part of the US 2010 Affordable Care Act and is currently a federal law. Since July 2008, the New York City (NYC) Health Department requires calorie contents of foods sold by catering businesses with over 15 outlets to be posted beside the price, in exactly the same font.2 Young adults, and specifically those in higher education, are particularly susceptible to weight gain.3 If this weight gain persists, it may lead to obesity. Calorie-labelling might have a particular value in preventing the weight gain observed in this age group as young adults often rely on meals eaten in catering outlets. This study aimed to review the current literature, conduct a meta-analysis and determine young adults’ views on calorie-labelling and on calories purchased. MATERIALS AND METHODS Literature review A review of the literature assessing the effect of calorie-labelling on calories purchased was conducted in 2014, using Pubmed/ OVID databases, with key words ‘labelling’ and ‘calories’ or ‘calorielabelling’ (English and American spellings). Inclusion criteria were: (1) examining the effect of calorie-labelling as an individually identifiable intervention in ‘real-life’ settings (2) published between 1990–2014. Studies on children and those of low quality were excluded. Study quality was assessed using the Cochrane risk of bias assessment tool (http://ohg.cochrane.org/sites/ohg.cochrane.
org/files/uploads/Risk%20of%20bias%20assessment%20tool.pdf). Two researchers (CKN and MEJL) independently assessed the studies for the inclusion criteria and quality. A meta-analysis was conducted using on-line software (http://www.meta-analysis.com/index.php). Young adult consumer survey The survey was reviewed and approved by Glasgow University Ethics Committee. An on-line questionnaire on lifestyle habits was sent to all first-year undergraduate students on admission. Three multiple-choice questions were included on current use of calorie labels, nutrition information that young adults would like to see in catering outlets and calorie-labelling on alcohol (full results of this questionnaire will be published elsewhere). Respondents’ characteristics and responses were examined statistically with χ2-tests, using SPSS 21 software (SPSS, Chicago, IL, USA). RESULTS Literature review Seven studies met the inclusion criteria, and seven were excluded, on the basis of quality or not meeting inclusion criteria (Table 1). Five studies included some risk of bias in methodology but there were two studies that were low risk and thus could be classified as ‘high-quality’. NYC legislation. Three studies4–6 examined the effect of the NYC legislation for compulsory calorie-labelling in chain restaurants, by collecting customers’ receipts and/or questioning customers’ views on labelling. None found any effect on calories purchased. Washington legislation. Two studies7 assessed the legislation enacted on 1 January 2009, which required calorie-labelling for chain restaurants with over 15 outlets and sales over $1 million
Department of Human Nutrition, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK. Correspondence: Professor MEJ Lean, Department of Human Nutrition, College of Medical, Veterinary and Life Sciences, University of Glasgow, New Lister Building, 10–16 Alexandra Parade, Glasgow G31 2ER, UK. E-mail:
[email protected] Received 24 April 2014; revised 4 July 2014; accepted 27 July 2014; accepted article preview online 1 September 2014; advance online publication, 30 September 2014
Calorie-labelling in catering outlets CK Nikolaou et al
543 Table 1.
Study characteristics and risk of bias according to Cochrane tool, studies excluded and reason for exclusion Studies characteristics
Cochrane risk of bias tool
Reference
Design/setting/intervention
Primary outcome measure method
Elbel et al.4
Cross-sectional NYC: intervention site Newark: comparator site calorie labels added in chain restaurants in the intervention site Cross-sectional Philadelphia: intervention site Baltimore: comparator site calorie labels added in chain restaurants Cross-sectional NYC calorie labels added in chain restaurants
Calories purchased before NYC: 21 kcal and after the calorie-labelling Newark: 3 kcal legislation (1 month interval). NS change Calories purchased from customers' receipts
Elbel et al.5
Dumanovsky et al.6
Krieger et al.7
Finkelstein et al.8
Chu et al.9
Pulos and Leng10
Results
Sequence Allocation Incomplete Selective generation concealment data outcome outcome reporting High risk
High risk
Low risk
Philadelphia:55 kcal High risk Baltimore: − 52 kcal NS change
Unclear
Low risk
Low risk
18 kcal NS change
Low risk
Low risk
Low risk
Low risk
No difference Low risk detected at 6 months. After 18 months: − 38.1 kcal at food chains, NS − 22.1 at coffee chains (P = 0.002) Natural experiment King Calories purchased before No difference High risk County, WA calorie labels and after the calorie-labelling detected at 8 or added in chain restaurants legislation (8 and 13 months 13 months interval). Calories ordered from customers' receipts Quasi-experimental Ohio Calories purchased− 12.4 kcal High risk State University, dining customers' receipts ‘before (P = 0.007) hall calorie labels added to and after’ calorie-labelling entrees Quasi-experimental Pierce Calories purchased ‘before −15 kcal High risk County, Washington and after’ calorie-labelling calorie labels added to entrees in six restaurants
Low risk
Low risk
Low risk
High risk
Low risk
Low risk
Unclear
Low risk
Low risk
Unclear
Low risk
Low risk
Calories purchased before and after the calorie-labelling legislation (4 months interval). Calories purchased from customers' receipts Calories purchased before and after the calorie-labelling legislation (8 months interval). Calories purchased from customers' receipts Cross-sectional King Calories purchased before County, WA calorie labels and after the calorie-labelling added in food chains and legislation (4–6 and coffee chains 18 months interval). Calories calculated from customers' receipts
Low risk
Studies excluded
Reason for exclusion
Harnack et al.15 Roberto et al.16 Hammond et al.17
Study conducted in laboratory setting Study conducted in laboratory setting Study conducted in laboratory setting
Abbreviation: NS, not significant.
per year. Calorie-labelling also became compulsory for drivethrough restaurants in Washington from August 2009. Finkelstein et al.7 found no effect either at 8 or 13 months post labelling. Krieger et al.8 found no effect at 6 months but a decrease of 22.1 kcal at coffee chains (P = 0.002) at 18 months post labelling. Entrees at independent catering outlets. Two US studies9,10 examined the effect of calorie-labelling on entrees only. Chu et al.9 found a mean decrease of 12.4 kcal per entree purchased from a university cafeteria (P = 0.007). Pulos et al.10 examined the effect of voluntary calorie-labelling in six independent restaurants. This study found reductions ranging from 16.8–55.6 kcal in four participating restaurants, and no change in the remaining two (Overall mean change = − 15 kcal). Gender effects. Four studies included analyses on the basis of gender. Dumanovsky et al.6 separated subjects who noticed the calorie labels according to gender, and found reductions for meals © 2015 Macmillan Publishers Limited
of 94.6 kcal for men (P = 0.003) and 99 kcal for women (P o0.001). Krieger et al.8 found a significant reduction of 65.4 calories for meals purchased by women (P = 0.01) but not for men. The two remaining studies4,5 found no gender effect. Meta-analysis Data on calorie differences and s.d. or 95% confidence interval (CI), allowing a meta-analysis, were available for six studies (Figure 1). The overall effect of calorie-labelling, including both meals and entrees alone was − 5.8 kcal (95% CI = − 19.4 to 7.8 kcal). The summary measure for two studies, which provided separate data on customers who reported noticing the calorie labels was − 124.5 kcal (95% CI = − 150.7 to − 113.8 kcal). Young adults’ survey Completed questionnaires were returned by 1440 young adults; response rate 48%, 67% females. Participants’ self-reported International Journal of Obesity (2015) 542 – 545
Calorie-labelling in catering outlets CK Nikolaou et al
544 Chu et al 2009 Elbelet al.2009 Pulos et al.2010 Dumanovsky et al.2011 Finkelstein et al.2011, 1 Finkelstein et al.2011, 2 Kieger et al.2013, 1 cc Krieger et al.2013, 1 fc Krieger et al.2013, 2 cc Krieger et al.2013, 2 fc
Summary measure: -5.8kcal (95% CI -19.4-7.8kcal)
-200
-150
-100
-50
0
50
Calorie difference (with label-without label per meal/entree) 1=time point 1, after 8 months 2=time point 2, after 13 months 1 cc=time point 1, after 6 months coffee chains 1 fc= time point 1, after 6 months food chains 2 cc= time point 2, after 18 months, coffee chains 2 fc=time point 2, after 18 months, food chains
Dumanovsky et al.2011 Krieger et al. 2013
Summary measure: 124.5kcal (95% CI-150.7--113.8kcal)
-200
-150
-100
-50
0
50
Calorie difference (with label-without label per meal/entree)
Figure 1. Meta-analysis of the differences between calories purchased with and without calorie-labelling: (a) for all meals or entrees in the six included studies; (b) for the subgroups who reported noticing the calorie labels.
characteristics were as mean (s.d.); age 20.3 (2.9) years, weight 65.9 (14.4) kg, height 1.72 (0.01) m and BMI 23.0 (4.6) kg m−2. About 46% of all respondents reported wanting calorie information, 34% not wanting it and 20% ambivalent. About a third of female and a quarter of male respondents would welcome calorie information at all suggested catering outlets (take-away restaurants, fast-food restaurants, university canteens and pubs). Half the female participants and a third of males reported that they would also like to see calorie information on alcohol. Females who said they wished no calorie information were heavier than those who wanted information (64.3 kg vs 61.9 kg, P = 0.03; BMI = 22.4 vs 21.7, P = 0.02). No similar relationship was found for men. DISCUSSION Two reviews were published on calorie-labelling studies in 2008 (n = 6) and 2011 (n = 7),11,12 the first concluding that evidence is International Journal of Obesity (2015) 542 – 545
scarce and more research is needed whereas the second concluded that calorie-labelling does not have the intended effect on calories purchased. The present literature review revealed only seven papers with adequate data. Importantly, no study showed any increase in calories purchased. The metaanalysis showed no overall effect on calories purchased, but among those who reported noticing the calorie labels (18% in Dumanovsky study and 58% at 6 months and 62% at 18 months in Krieger study), the effect was significant, at − 125 kcal. Saving 125 kcal daily would result in a saving of 45 260 kcal per year, which would avoid a weight gain of about 6 kg per year. The average annual weight gain in adults is small, around 0.7 kg per year, but obviously greater in those who become obese, so calorie-labelling clearly has capacity as a simple weapon against the obesity epidemic. The superior effect of calorie-labelling among those noticing the calorie labels indicates its value for people who want to © 2015 Macmillan Publishers Limited
Calorie-labelling in catering outlets CK Nikolaou et al
545 control their weights, but the lack of effect in others may reflect inappropriate labelling presentation or lack of educational supporting material and guidance. The two studies from independent catering facilities found significant effects but do not report the labelling format they used: their presentation may have been different from that required by the US calorie-labelling legislation. Given that so many young people would like to avoid weight gain, having very visible calorie labels is important. From our survey, young adults generally seem to be in favour of the provision of nutrition information notion with women appearing more receptive than men, supporting previous evidence.13 Among the studies that assessed the effect of calorie-labelling legislation, there was a large variation in elapsed time between implementation of the legislation and data collection. Krieger et al.8 collected data at two time points after legislation went in place (6 and 18 months) and found a significant effect only after 18 months, so the timing of studies after the implementation of the law may be important in a setting where the customers vary daily. It may take time for customers’ familiarity with calorie information to affect calories purchased. On the other hand, consumers can be resistant to adopting lifestyle change and become ‘blind’ to information provided ubiquitously, like the health messages on cigarettes.14 However calorie information is used by industry voluntarily, so clearly has value for marketing. Marketing interventions to change behaviours seem to have effects which increase gradually over time, so long-term observation is necessary along with revision of the public health message around calorie-labelling. Only one of the studies reported responses from the caterers. Pulos and Leng10 who examined the voluntary effect of labelling reported reformulation of recipes and changes in portion sizes after the initial analysis. Assessing the caterers’ responses to calorie-labelling is critical for sustainability. ‘Nudging’ consumers towards better-informed choices can lead potentially to menu reformulations by working closely with the catering providers. This review included only studies conducted in real-life settings. Three other studies15–17 were conducted in closed laboratory settings by randomising participants to groups that received calorie information, no information or other information. The ‘laboratory setting’ studies cannot represent a realistic environment in which customers make food choices: participants were informed about study aims, which may have influenced results while under observation. Focussing on calorie contents for the purpose of a laboratory study cannot replicate the complexity behind day-to-day real-life food choices, with competing influences from factors such as taste, price, convenience and social relationships.18 CONCLUSION Calorie-labelling is a low-cost intervention, which can be easily implemented. Many young adults are receptive to the idea of calorie-labelling in catering outlets and alcoholic drinks. Current evidence supports the notion that it may help against
© 2015 Macmillan Publishers Limited
weight gain and obesity, especially among those noticing calorie-labelling. CONFLICT OF INTEREST The authors declare no conflict of interest.
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