Associations between exposure to takeaway food outlets, takeaway food consumption, and body weight in Cambridgeshire, UK: population based, cross sectional study
BMJ 2014; 348 doi: https://doi.org/10.1136/bmj.g1464 (Published 13 March 2014) Cite this as: BMJ 2014;348:g1464
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After reading the interesting article by Burgoine et al. I was at first irritated by the lack of a table to compare the characteristics (as shown in Table 1) of participants grouped according to quarters of take-away environment. Further, I missed a simple presentation of outcome variables (mean take-away consumption, mean BMI, percentage overweight and obese) grouped according to these same quarters. Usually one would expect such tables in order to assess the comparability of the groups with respect to possible confounders and for a direct, unadjusted comparison of outcomes, respectively.
Then I discovered this information in Web table 3 of the online appendix. Here, we see systematic differences between quarters with respect to education, smoking and car ownership. I think the authors should have presented these tables and drawn attention to these differences in the main printed article, even if the multiple linear regression models adjusted for the covariables concerned.
What surprised me even more in Web table 3 was the fact that mean take-away consumption was slightly inversely correlated with combined take-away availability, varying between 36.3 g/day in Q1 and 34.2 g/day in Q4. This contrasts completely with the results of the multivariate analysis (Fig. 1) in which a significant positive correlation between take-away availability and consumption was obtained. Moreover, In Web table 3 mean BMI is almost constant in all quarters of take-away availability, contrasting with the significant positive correlation between take-away availability and BMI derived from the multiple linear model (Fig. 2). While I accept that the multivariate analysis adjusting for potential confounders is the analysis of choice for such an observational study, the complete lack of agreement with the simple univariate analysis is worrying and should be presented and discussed.
A hint on the possible explanation for these inconsistencies is given under ‘sensitivity analyses’. ‘In models that omitted supermarket exposure as a covariate, the associations between combined take-away food outlet exposure, consumption of take-away food and body mass index were attenuated towards the null…’. These sensitivity results are given in Web figures 5 and 6. The expression ‘attenuated towards the null’ is an understatement: no association remains at all, in agreement with the simple univariate comparison. Thus, supermarket exposure and take-away exposure seem to interact with each other in their relationship to take-away consumption and BMI. Possible, the results obtained reflect not just take-away outlets but the type of environment as a whole, for instance, rural versus urban. Information on supermarket exposure and urban/rural residence (possibly also urban/rural work-place) per quarter should have been included in Web table 3.
In summary, the incomplete presentation of results in the printed article tends to obscure inconsistencies which shed doubt on the conclusions drawn.
Competing interests: No competing interests
Flanagan and Yeung (25 April) are somewhat critical of this paper from the Cambridge Institute of Public Health. I ask: up in Glasgow you have no doubt adequate facilities to mount a study addressing the deficiencies perceived by you. Are you considering such a study?
Secondly, I raised in my earlier rapid response the idea that in the light of the Cambridge findings, the directors of public health, the royal colleges might get out of their lethargy - or is it deep contemplation? - and actually do something to seek closure of some of these Tempters of the Tongue.
Would Flanagan and Yeung, or for that matter anyone else in the business of protecting public health, disagree?
Thank you
Competing interests: I like to see public health consultants actually doing something on the "ground".
Burgoine et al have carried out a painstaking study. Congratulations and thanks.
Now the question arises: will the government do something?
I suspect not - unless it is badgered. There should be a two-pronged attack. The Faulty of Public Health, Royal College of Physicians and the RCPCH should pummel the Central Government. The Second Front should be opened by the Directors of Public Health, who should, unless banned by their employers, conduct a survey of fast food outlets near schools, colleges, universities, and recommend a ban on the opening of new and replacement outlets. The Directors will not be popular but then popularity and patronage of a harmful industry are never compatible.
Competing interests: None
It makes intuitive sense that an increased number of takeaway outlets would result in more people accessing these outlets. Takeaway outlets are also more likely to produce and sell foods considered to be less healthy and less likely to contain components of a healthy balanced diet (1). For example, takeaway foods are thought to be high in calories and contain high levels of fats, trans fatty acids, salt and carbohydrates and the Food Standards Agency in Scotland is in the process of researching this (2). It also makes intuitive sense that consuming more of these types of foods would result in an increase in BMI or overweight and obesity. However, due to the study design these results cannot prove a causal link between an increased prevalence of takeaway outlets and increased food consumption and this was duly acknowledged by the authors.
Due to the sheer complexity of overweight and obesity there are a number of potential confounders which have not been considered. These include the types of food consumed, calorie content and ethnicity with the latter being a surprising omission due to the proximity of Cambridge to London. Also, it seems quite arbitrary why some takeaway food outlets were used and not others. The popularity of Chinese and Indian takeaway food outlets in the UK has not been assessed in this study and these foods could arguably be less nutritious than other food outlets included in this study. The 1 mile radius used in this paper may also not be a useful distance to accurately assess access to outlets due to the availability of delivery services and the increasing popularity of websites offering online ordering options. Food affordability is also a factor which can influence purchasing patterns and it has been well documented that takeaway outlets are often cheaper than healthier alternatives (3).
A crucial area that this research does not discuss is the association between social norms and obesity. Living in an area and having regular exposure to takeaway outlets on a daily basis will result in these food outlets becoming the norm. This is similar to regular exposure to smoking, drugs and alcohol. Regular exposure to these outlets results in them becoming more acceptable and less shocking. In populations where this is the norm people are more likely to adopt these behaviours themselves (4, 5). In fact, in some communities if you actively go against these norms you may risk being stigmatised. As has been described in many studies before this, these risk factors are often seen in more deprived areas (6). However, this study is unlikely to be able to fully demonstrate this as it was based in a more affluent area.
The complexity of overweight and obesity has been acknowledged and demonstrated in research such as the obesity system map in the Foresight report (7). While it makes sense that regular exposure to takeaway foods and outlets would affect food choices and potentially result in an increased consumption, nobody forces us to eat junk food. A number of fast food outlets also offer healthy alternatives and an increasing number are now displaying nutritional information on their menus. Ultimately, your risk of obesity can be influenced by the choices you make. You choose where and what you eat. Exposure to food outlets alone is unlikely to explain the increase in overweight and obesity and the cause is likely to involve a combination of several factors such as lifestyle, diet, activity, deprivation and cultural and social norms that are contributing to the nation’s growing waistlines. The food environment may well be an additional factor but it is unlikely to be the only contributing factor.
1.Food Standards Agency in Scotland. The eatwell plate. http://www.food.gov.uk/scotland/scotnut/eatwellplate
2.Food Standards Agency in Scotland. Food Standards Agency in Scotland Evidence-Gathering Programmes. http://www.food.gov.uk/science/research/devolvedadmins/scotlandresearch/...
3.NHS Choices. Healthier takeaways. http://www.nhs.uk/Livewell/men1839/Pages/Dodgytakeaways.aspx
4.Robinson E, Thomas J, Aveyard P, Higgs S. What Everyone Else Is Eating: A Systematic Review and Meta-Analysis of the Effect of Informational Eating Norms on Eating Behavior. J Acad Nut Diet 2014;114:414-29.
5.Hruschka DJ, Brewis AA, Wutich A, Morin B. Shared Norms and Their Explanation for the Social Clustering of Obesity. Am J Public Health, 2011;101(Suppl 1):S295–300.
6.Miura K, Giskes K, Turrell G. Socio-economic differences in takeaway food consumption among adults. Public Health Nutr 2012;15:218-26.
7.Foresight. Tackling obesities: Future choices – project report. 2nd edition. London: Foresight, Government Office for Science, 2007. http://www.bis.gov.uk/assets/foresight/docs/obesity/17.pdf
Competing interests: No competing interests
Re: Associations between exposure to takeaway food outlets, takeaway food consumption, and body weight in Cambridgeshire, UK: population based, cross sectional study
Burgoine et al pointed the finger at unhealthy take-aways a year ago. Today's Guardian, page 9 carries a report by Dennis Campbell on "Britain's unhealthiest streets". It is based on a report from the Royal Society for Public Health. In brief, "more high streets are being overtaken ( sic ) by tanning salons, take-aways, bookmakers.....
Those who have lived long enough will recall that fish and chip shops used to be the only fast-food outlets. Then came Chinese take-aways, then "Indian" (read Sylheti) take-aways, then delivered pizzas.
Every local authority has, naturally, a passion for small businesses. Our local and national governments seem to believe in a totally unregulated free for all.
Health education is fine. But unless governments encourage people to cook (make it profitable for corner shops to sell uncooked meat and vegetables), restrict the shelf space of supermarkets given over to ready meals, indeed impose punitive taxes on ready foods (yes, even on Cornish pasties), subsidise uncooked vegetables, restrict the numbers of fast food outlets to, say, city centres, bus stops, railway stations, there is little likelihood of people being encouraged to cook healthy food.
Every local authority has a director of public health. Have any of these authorities asked the DPH to inspect, assess, advise on such unhealthy "facilities" for "busy" workers? I suspect not.
Competing interests: Rarely I eat fish and chips. Yesterday was such a " blue moon" event.