“Trillion” isn’t a word you use much in obesity research. Particularly not when you study interventions that typically have modest goals – a BMI unit if you’re lucky, maybe a few minutes of physical activity. I’ve never heard of an intervention that produced trillions of anything.
So it was a big deal last week when investigators from the University of North Carolina-Chapel Hill (UNC) reported that Americans bought 6.4 trillion fewer calories from major food companies in 2012 compared to 2007.
It was an even bigger deal because those food companies were taking credit for it.
In 2010, Coca-Cola, General Mills, and 14 other food-manufacturing companies made a pledge to sell 1 trillion fewer calories by 2012 and 1.5 trillion fewer calories by 2015. The companies, who are part of a coalition known as the Healthy Weight Commitment Foundation (HWCF), advertised it as their effort to help reduce childhood obesity. Some people hailed this as a major step forward; others dismissed it as an empty PR stunt.
To settle the debate, the Robert Wood Johnson Foundation (RWJF) hired an independent research team from UNC to evaluate the pledge. UNC investigators had the complex task of answering the simple question, “Did HWCF companies do what they said they would do?”
The companies pledged a 1 trillion calorie reduction by 2012 and we got a 6.4 trillion calorie reduction instead, so the answer to that question might seem straightforward. But nothing ever is.
The UNC research team did a phenomenal evaluation. “Rigorous” is usually a complement when describing research studies; in this case, “rigorous” would be a criminal understatement. (I should confess that 2 of the authors are friends of mine, but my friends can attest that I’m stingy with compliments. I don’t praise something if I don’t mean it.)
Unfortunately, what is gained in rigor can be lost in translation. The only thing harder than a Herculean data analysis is communicating it. The investigators did more analyses in 2 studies than I will do in the next 20 years, and the volume and sophistication of their analyses led to some miscommunication in the media over what they found exactly.
So what did we learn about the HWCF pledge and what did we not learn?
3 things we learned about the HWCF pledge
- HWCF companies did what they said they would do
Did they sell 1 trillion fewer calories by 2012? Yes, and then some. Nobody can deny that.
- HWCF companies were already selling fewer calories before the pledge. So was everybody else.
The 2008-2012 decline was largely a continuation of market trends from 2000 to 2007, when all food companies were steadily selling fewer calories. There is nothing to suggest that HWCF companies made any revolutionary changes after their pledge. In fact, according to the UNC investigators, the decline in calories should’ve been greater if HWCF companies maintained their pre-pledge trends (after you account for socioeconomic trends over time.)
- Post-pledge changes in calorie sales were greater in companies that were not part of the HWCF
Companies that didn’t make any bold promises actually saw a greater drop in calorie sale trends after the HWCF pledge. This is a story we’ve heard before – companies that promised to regulate marketing of unhealthy food to children were found to market more unhealthy foods to children than companies that didn’t make any promises.
3 things we did NOT learn about the HWCF pledge
- Whether American are eating fewer calories
Contrary to some news headlines (“Households with kids ate less junk food”), the studies reported nothing about what Americans eat. That wasn’t their objective. The studies were designed to analyze what Americans buy, not what they eat.
- Whether Americans are buying healthier foods
“Fewer calories” and “healthier” are 2 different things. HWCF companies likely cut calories, in part, by selling reformulated versions of high-calorie products, which doesn’t necessarily mean these products are healthy. As dietitian Andy Bellatti eloquently tweeted back in January, when RWJF first hinted at the study results, “A 100-calorie pack of Cheetos, after all, is not a better choice than a 130-calorie apple.”
- At the end of the day, what drove the decline in calorie sales?
As the UNC investigators extensively discussed, there are many, many demand- and supply-side factors that could explain the decline in calorie sales (e.g., the Great Recession that coincided with the beginning of the pledge.) There is no way to figure out what ultimately drove the decline. Again, there is nothing in the data to suggest that HWCF companies made any major changes as a direct result of the pledge. Anything they did may have simply been a continuation of market trends.
Overall, should we be encouraged by the results? Depends who you ask. Some people have applauded the food industry while others dismissed the results. The most level-headed response came from the authors, who sounded cautiously optimistic in both studies and media reports.
It’s hard to make a case that 6.4 trillion fewer calories in the U.S. food system is a bad thing. Should we throw the HWCF companies a parade for it? Not when we don’t know yet how the decline translates into the overall health of Americans’ diet. All we know is that 6.4 trillion calories aren’t what they used to be. Where did they go? At this point, nobody knows.
A story to be continued …