Monday, December 16, 2013

Using Advertising to Improve Diet

The post for today was written, by me, as an exercise for a class I am taking to improve my writing.  I chose the study for blog relevance and personal interest, but it may seem more formal than my usual, opinion- infused posts.  Now you know why :)

 In the United States, obesity rates have risen over the past 40 years (Ogden & Carroll, 2010), and many health professionals consider the disease to be epidemic.  The suggested causes of obesity are numerous, interconnected and multi-level.  Because individual level prevention programs are expensive and generally ineffective, researchers have begun testing environmental or societal level strategies that can affect whole populations (Swinburn, Egger, & Raza, 1999).  For example, Rusmevichientong, Streletskaya, Amatyakul and Kaiser (2014) recently conducted a laboratory experiment to compare the effect of 4 types of food advertising on lunch purchases.  The researchers expected that limiting unhealthy food advertising, increasing healthy food advertising and airing anti-obesity messages would each lead to the purchase of items with less calories, fat, sugar and sodium.

If advertisement manipulation is effective in reducing over consumption in the short term, public health advocates will have evidence to promote advertising interventions or policies, which may lead to a reduction in obesity rates over the long term.  Rusmevichientong and colleagues offer some evidence in this regard.

 Rusmevichientong and colleagues randomly assigned 182 adult college students into one of 4 treatment conditions.  All participants watched TV for about 16 minutes. In all but one group (the control), the participants viewed four, five or six, 30 to 60 second advertisements in one of the following categories: unhealthy food advertisements (unhealthy foods were defined as items high in sugar, fat and sodium), healthy food advertisements (ones promoting the consumption of fruits and vegetables), anti-obesity messages, and a mixture of all three types. Before and after the TV viewing, each participant chose a lunch meal from a computerized menu.  The researchers provided $10 meal vouchers, but participants had to pay the difference if their order was more than $10.  The researchers compared the food orders before and after the TV viewing (within participants) and the changes between the groups, including the control. The research design (different in difference) allowed the researchers to compare the magnitude of difference between ad types.

In this laboratory experiment; exposure to the healthy food messages, anti-obesity messages and a mixture of unhealthy, healthy, and anti-obesity messages, led to an increase in healthy food purchases and a decrease in number of calories purchased. The healthy food messages produced the greatest decrease in calories purchased (134) compared to anti-obesity messages (93) or mixed messages (90). There was also some reduction in the fat and sodium content in the meals purchased.  In addition, Rusmevichientong and colleagues found a positive association between these 3 advertisement conditions and ‘becoming healthier,’ which they defined as purchasing a greater number of healthy foods at time 2.  The researchers suggest using anti-obesity ads judiciously and thoughtfully (i.e., ones that are not stigmatizing or fear producing) and healthy food advertising to reduce the over consumption of calories in the US adult population.
Rusmevichientong and colleagues results are important because most research suggesting a relationship between both anti-obesity messages and reduced caloric consumption, and healthy food ads and reduced caloric consumption is based on cross sectional surveys.  Experimental studies allow researchers to claim causal inference, e.g., healthy food ads change behavior. However, this particular study was small, took place outside of a natural setting and used a homogenous set of participants.  Policy advocates may present this evidence along with evidence produced from representative, field based, cross-sectional or longitudinal studies to make a case for new advertising polices.

Ogden, C. L., & Carroll, M. D. (2010). Prevalence of overweight, obesity, and extreme obesity among adults: United States, trends 1960–1962 through 2007–2008. NCHS Health and Stats.
Rusmevichientong, P., Streletskaya, N. A., Amatyakul, W., & Kaiser, H. M. (2014). The impact of food advertisements on changing eating behaviors: An experimental study. Food Policy, 44(0), 59-67. doi:
Swinburn, B., Egger, G., & Raza, F. (1999). Dissecting obesogenic environments: The development and application of a framework for identifying and prioritizing environmental interventions for obesity. Preventive Medicine, 29(6), 563 - 570. doi: 10.1006/pmed.1999.0585


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