Food choice & traffic lights

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The following is a guest post from Harold DeMonaco, MS, one of our story reviewers on  The opinions are his.


In April of this year, I wrote a guest blog post in which I suggested that healthcare workers did not seem to be very good role models with regard to obesity.  While a number of interventions have been attempted (including Mayor Bloomberg’s proposed ban on giant soft drinks in New Your City, labeling food calorie content and others), most have not produced repeatable results. At the risk of being accused of serving as an arm of marketing for the Massachusetts General Hospital, I want to point out a rather interesting study.

The August edition of the American Journal of Preventive Medicine includes an article (link to pdf file) by researchers at the MGH that adds a bit of new information to our understanding of how to deal with the obesity epidemic.

The idea under study is appealingly simple; color coding food choices in the hospital’s cafeteria.  In addition, the display placement of healthy choices was optimized.

The study examined in purchases of about 4600 employees over a 9 month period, starting prior to the introduction of the “traffic light” labeling program, followed by the food placement changes.  The results were recorded based on employee’s self-identification of ethnicity.

Here are the results:

Employees self-identif?ed as white (73%); black (10%); Latino (7%); and Asian (10%).

Compared to White employees, Latino and Black employees purchased a higher percentage of red items at baseline (18%, 28% and 33%respectively, p<0.01.  Labeling decreased all employees’ red item purchases (–11.2%,95%CI_–13.6%,–8.9%)and increased green purchases (6.6%,95%CI_5.2%,7.9%). Red beverage purchases decreased most (–23.8%,95%CI_–28.1%,–19.6%). The choice architecture intervention further decreased red purchases after the labeling. Intervention effects were similar across all race/ethnicity and job types (p_0.05 for interaction between race or job type and intervention).

Mean calories per beverage decreased similarly over the study period for all racial groups and job types, with no increase in per-beverage spending.

The authors concluded:

Despite baseline differences in healthy food purchases, a simple color-coded labeling and choice architecture intervention improved food and beverage choices among employees from all racial and socioeconomic backgrounds.

Of course, no single study is definitive and it remains to be seen if the results are reproducible in other healthcare and non-healthcare settings.  But would it not be interesting to see what would happen if this system were implemented in fast food franchises?


Note:  Katherine Harmon also reported on the study for Scientific American.

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