Fast food and obesity: Why it may not be about the calorie

We’ve all heard the familiar chorus: fast food is one of the main reasons for our current obesity epidemic. Almost always the reason is some combination of calories, fat, sugar, and salt. But the underlying rationale always has to do with “overconsumption of calories.”

Well, a new study published a couple months ago suggests an alternative theory. Instead of calories, per se, what if it was because of something else? What if it had to do with the way the food is processed and prepared?

A team of researchers from my alma mater, the George Washington University School of Public Health, analyzed the associations between recent fast food intake and several known “endocrine disruptors,” such as BPA, di(2-ethylhexyl) phthalate (ΣDEHPm), and diisononyl phthalate (DiNPm).

Research in both animals and humans have found phthalates and BPA exposure to be linked to obesity.  Phthalates’ use in plasticizers dates back to the 1930’s, and many common personal care products (e.g., perfumes, lotions, cosmetics, shampoo), toys, and others household products with plastic contain these compounds.

Until now, though, no one really thought of phthalate exposure via fast food consumption. The results of this study suggest maybe we should.

Researchers used data on 8877 participants from the National Health and Nutrition Examination Survey from 2003-2010 and found a positive, dose-response association between fast food intake and di(2-ethylhexyl) phthalate anddiisononyl phthalate. They also found that

“participants with high fast food intake had 20-40% higher urinary concentrations of phthalate metabolites than non-consumers.”

Now, because this was a cross-sectional study there is no way of knowing whether the association is causal. In other words, we can’t say that fast food consumption was the source of participant’s phthalate exposure. It could just be that people who eat the most fast food are also exposed to phthalates from other environmental sources, like personal care products.

Either way though, the findings are interesting in the context of the complex web of factors that may influence obesity’s etiology, and, if anything, highlight the growing ubiquity of phthalates and other known industrial chemicals that influence human health.


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