Science is a wonderful tool for understanding how our world really works. But if the science supporting a given understanding is flawed, or worse, if it is slanted in favor of a politically-favored outcome, it can become the justification for excessively wasteful activities. When science crosses that line, it is transformed from something that is worthy of respect into junk science.

This is the story of Michelle Obama and her fight against the food deserts of America. The story begins on 24 February 2010, when the First Lady of the United States of America used her White House platform to introduce the little-understood concept of the newly-discovered "food deserts" of America to Americans as part of a media blitz:

As part of Lets Move!, the campaign to end childhood obesity, First Lady Michelle Obama is taking on food deserts. These are nutritional wastelands that exist across America in both urban and rural communities where parents and children simply do not have access to a supermarket. Some 23.5 million Americans – including 6.5 million children – currently live in food deserts. Watch the video below and learn what the First Lady is doing to help families in these areas across the country.

Food deserts sound horrible. Isn't it good that the First Lady is doing something about this awful problem that would appear to be plaguing America's most poor, yet obese citizens, who suffer because they are deprived from having large supermarkets stocked with nutritious foods within walking distance of where they live?

Or is the First Lady relying upon junk science to justify the wasteful expenditure of taxpayer money to benefit her and the President's political cronies? After all, there was already plenty of evidence back in 2010 that indicated that food deserts were more a junk science-fueled political talking point than a real factor that significantly contributed to making poor Americans obese, as the original 2006 study proclaiming the crisis in President Obama's home base of Chicago was funded by LaSalle Bank of Chicago, then the largest business lender in the city, who would directly profit from investments to "remedy" the situation.

Fortunately, respectable science can help provide the answers to these questions. The U.S. Centers for Disease Control very recently published a peer-reviewed scientific study of the impact that a lack of nearby access to nutritious foods, such as might be found in one of the First Lady's food deserts, actually has upon the Body Mass Index (BMI) of the Americans who live within such regions. Here are the results and conclusion for their study of 97,678 adults in the state of California (home to 1 out of every 8 Americans):

Results

Food outlets within walking distance (≤1.0 mile) were not strongly associated with dietary intake, BMI, or probabilities of a BMI of 25.0 or more or a BMI of 30.0 or more. We found significant associations between fast-food outlets and dietary intake and between supermarkets and BMI and probabilities of a BMI of 25.0 or more and a BMI of 30.0 or more for food environments beyond walking distance (>1.0 mile).

Conclusion

We found no strong evidence that food outlets near homes are associated with dietary intake or BMI. We replicated some associations reported previously but only for areas that are larger than what typically is considered a neighborhood. A likely reason for the null finding is that shopping patterns are weakly related, if at all, to neighborhoods in the United States because of access to motorized transportation.

Economist Jacob Geller reviewed the study's statistical results:

If you look at the statistical tables, they’re pretty striking. Even where there is statistical significance — which is the exception to the rule — the size of the effect is so tiny, it’s like practically nothing. For example, on the margin, adding one full-service supermarket within a one-mile radius of your house is associated with an average BMI decrease in your neighborhood of .115. That is a difference of just one pound. (see back-of-the-envelope calculations here)

So there is really no relationship, according to this one recent study of nearly 100,000 Californians, between the distance between your body and a full-service supermarket (or any other kind of food store), and whether or not you are obese. Distance, which is a proxy for access (the idea of a food desert is that the nearest supermarket, which has fresh produce, is distant), is for all practical purposes a non-factor.

We created the following tool so you can see what Michelle Obama's publicity campaign to direct large and/or politically well-connected retailers to spend millions of dollars to open or expand stores in the "disadvantaged" regions identified by the U.S. government as supposed food deserts would have in terms of your own weight. And the cool part is that the math is such that we can figure out just how much that would be for you from just your height!

Our tool indicates how much of your weight would be affected by whether you lived within a food desert. If you live in an area identified by the U.S. government as a food desert, it indicates how much more you would weigh, and if you were to move out of that area, it is how much you would lose. To put your result into proper context, the weight of an adult American normally fluctuates by up to 5 pounds during the course of a single day.

Did we mention large and/or politically well-connected retailers are involved? That's actually how we know that the whole food desert publicity campaign is really about crony capitalism more than it is about dealing with the health problems of obesity. Because in truth, if it were a real problem that could be fixed by opening new store locations, it would be a lot easier, cheaper and faster for small "Mom and Pop"-style grocery businesses to fit themselves into the already existing and available retail spaces within such deprived communities as the supposed food deserts of America.

But since the whole food desert concept would seem to be based on junk science rather than the more respectable kind, it is perhaps too much to ask for the solutions advanced by the politicians taking charge of the crisis to solve a legitimate problem.

References

Carras, Michelle Colder. Normal Body Weight Fluctuation. LiveStrong.com. http://www.livestrong.com/article/29567-normal-body-weight-fluctuation/. 7 May 2011.

Croft, Cammie. Food desert? What’s a food desert? White House Blog. http://www.whitehouse.gov/blog/2010/02/24/taking-food-deserts. 24 February 2010.

Gallagher, Mari. Examining the Impact of Food Deserts on Public Health in Chicago. http://www.marigallagher.com/site_media/dynamic/project_files/Chicago_Food_Desert_Report.pdf. Mari Gallagher Research & Consulting Group, sponsored by LaSalle Bank. 2006.

Geller, Jacob A. The Problem of "Food Deserts" Is Not All About Access. http://jacobageller.com/2013/04/the-problem-of-food-deserts-is-not-all-about-access/. 3 April 2013.

Hattori A, An R, Sturm R. Neighborhood Food Outlets, Diet, and Obesity Among California Adults, 2007 and 2009. Prev Chronic Dis 2013;10:120123. DOI: http://dx.doi.org/10.5888/pcd10.120123. 14 March 2013.

McWhorter, John. The Root: The Myth of the Food Desert. National Public Radio. http://www.npr.org/2010/12/15/132076786/the-root-the-myth-of-the-food-desert. 15 December 2010.

Mooney, Alexander. First Lady Takes on 'Food Deserts'. CNN: The 1600 Report. http://whitehouse.blogs.cnn.com/2011/07/20/first-lady-takes-on-%E2%80%98food-deserts%E2%80%99/. 20 July 2011.

Political Calculations. How To Detect Junk Science. http://politicalcalculations.blogspot.com/2009/08/how-to-detect-junk-science.html. 19 August 2009.

White House. Transcript of President Obama's Remarks at 2013 White House Science Fair. White House Photos and Video. http://www.whitehouse.gov/photos-and-video/video/2013/04/22/president-obama-tours-2013-white-house-science-fair#transcript. 22 April 2013.

Wright, Ann. Interactive Web Tool Maps Food Deserts, Provides Key Data. http://www.letsmove.gov/blog/2011/05/03/interactive-web-tool-maps-food-deserts-provides-key-data. LetsMove.gov. 3 May 2011.

Update 27 March 2022: The original video hosted at the White House's web site is no longer available. We've replaced it with a copy still available on YouTube.