One central assumption of those advocating prohibiting soda purchases with food stamps is that poor people are obese. The question, in my mind, is whether excess weight is associated with income.

I did not find any research that showed a consistent and clear pattern between income and excess weight. It does not mean that there is no data, but none has jumped out at me so far.

Highlights from the Journal of the American Medical Association (JAMA) reported data for preschool-aged children living in low-income families from 1998 to 2010 in December 2012 (Volume 308, No. 24).

They reported that extreme obesity and obesity declined among low-income increased from 1998 to 2003, and then decreased from 2003 to 2010, although the rates were higher than they were in 1998.

The prevalence of extreme obesity:

1998                2003               2010

1.75%              2.22%           2.07%

The prevalence of obesity

1998                 2003                 2010

13.05%            15.21%           14.94%

However, they did not provide data for children in non-poor households, so there is no way to determine whether obesity is a low-income problem requiring special policies targeted solely at the poor.

One study, titled “US food assistance programs and trends in children’s weights” looked specifically at the belief that providing food assistance “encourages participants to consume too much food.” The study was conducted by Michele Ver Ploeg et al. who work for the USDA’s  Economic Research Service. It was published in the International Journal of Pediatric Obesity in  2007. They looked at  the food stamp program and the Special supplemental nutrition program for Women, Infants and Children (WIC).

They used data from multiple waves to the National Health and Nutrition Examination Surveys between 1976 and 2002.  They did not find a consistent pattern between participation in food programs and BMI. There was some variation by ethnic group and in some comparisons (age, gender, race), the children from higher income sometimes had a statistically significant lower probability of having excess weight. And it was also true that some of the results showed a lower probability of excess weight for some groups than others. Their conclusion: “Our results show an inconsistent association between FSP participation and weight for school-aged children.”

They also note also note that the programs themselves have changed over time, so the comparisons over time are apples and oranges.

In my view, the best study would be a panel study that tracks the same children over time, including very specific information about nutrition: what are they eating from the moment of birth.

I was curious about what is in formula. I was at a very upscale food store with lots of organic and natural foods and decided to check. I don’t know if the formula they had could be bought with food stamps or WIC vouchers, and I don’t know if they are different from ordinary formula found in non-upscale food stores. But they did indeed have sweeteners. Really. I will get to sugar and high fructose corn syrup in another post and the role sweeteners play in the issue of obesity.

What about adults? Based on data in from Table 74 from Health, United States, 2011, we can see changes in weight in the adult population over age 20. The table also provides a breakout based on percentage of the poverty level. There is some difference among those below the poverty line, but these are not big. Clearly, whatever factors are causing a rise in excess weight are pretty much cutting across society and all income groups have shown a general increase over time. If government intervention is needed, it will have to be one that cuts across the population rather than one narrowly targeted to the poor.

Adults, 20 years and over, Percent of Population

Source: National Center for Health Statistics. Health, United States, 2011: With Special Feature on Socioeconomic Status and Health. Hyattsville, MD. 2012.

So, returning to Bittman’s argument about food stamps and soda:  at this point, I would conclude that obesity is not a greater problem among the poor. Therefore,  I would argue that it does not make much sense to target the poor if the intention is to reduce excess weight in the American population. A policy intervention has to address all groups. And that means we have to understand the causes. so, the next questions are whether soda is a key factor and whether policies restricting soda consumption is likely to have an impact.