As many are aware, an obesity epidemic is raging across the United States. Many factors are contributing to the problem and now UCLA researchers have unearthed another one: outdoor advertising. In addition, previous research by the same authors found that fast food ads are more prevalent in low-income, minority areas. The researchers published their findings online in the journal BMC Public Health on January 10.
The researchers note that past studies have suggested a relationship between neighborhood characteristics and obesity, as well as a connection between obesity and advertisements on television and in magazines. The new study has found a link between outdoor food advertisements and obesity among residents in the area. “Obesity is a significant health problem, so we need to know the factors that contribute to the overeating of processed food,” noted Dr. Lenard Lesser, who conducted the research while a Robert Wood Johnson Foundation Clinical Scholar at the UCLA Department of Family Medicine and UCLA’s Fielding School of Public Health. He added, “Previous research has found that fast food ads are more prevalent in low-income, minority areas, and laboratory studies have shown that marketing gets people to eat more. This is one of the first studies to suggest an association between outdoor advertising and obesity.”
For the study, the researchers examined two densely populated areas in Los Angeles and New Orleans, each with more than 2,000 people per square mile. They focused on more than 200 randomly selected census tracts from those two areas, which included a mixture of high- and low-income residents. They used data on outdoor food advertising in those areas gleaned from a previous study on ads and alcohol consumption (which had tracked all the outdoor ads). They then linked that information with telephone-survey data from the same study, in which nearly 2,600 people between the ages of 18 and 98 from those areas were asked health-related questions in addition to questions about their height, weight, self-reported body mass index (BMI) and soda consumption.
The investigators found that the higher the percentage of outdoor ads for food, the higher the odds of obesity in those areas. Dr. Lesser explained, “For instance, in a typical census tract with about 5,000 people, if 30% of the outdoor ads were devoted to food, we would expect to find an additional 100 to 150 people who are obese, compared with a census tract without any food ads.”
The authors noted that because the study focused on only two areas, they recommended further research to determine if the findings would be replicated in other areas. Because the study was cross-sectional, the researchers do not claim that the ads caused the obesity. They also note that self-reported information about weight is subject to recall bias, and people often under-report their true weight.
The researchers concluded that an important contribution of their study was that it demonstrated that outdoor advertising is associated with a modest, but clinically meaningful, increased likelihood of obesity. They explained that a reasonable way to prove a causal relation would be to reduce outdoor food advertising in certain neighborhoods and determine whether obesity rates change. If the above associations are confirmed by further research, they had some suggestions that might address the problem. They noted that bans on certain kinds of alcohol ads have reduced consumption in many nations. Efforts to control the placement of a particular type of outdoor advertising are likely to be deemed unconstitutional in the United States; however, requiring warnings on those advertisements are likely to be constitutionally acceptable. They suggested innovative strategies, such as warning labels, counter-advertising, or a tax on obesity-promoting advertising should be tested as possible public health interventions for reducing the prevalence of obesity.