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Food Stamps and Obesity: What Do We Know?
Michele Ver Ploeg and Katherine Ralston
Economic Information Bulletin No. (EIB-34) 37 pp, March 2008
The Food Stamp Program provides benefits for low-income individuals to purchase food at grocery
stores. The program was begun in the 1960s and expanded in the 1970s at a time when a problem
facing many Americans was underconsumption of food and nutrients. Today, however, the primary
nutrition problem facing the U.S. population has shifted from too little intake to overconsumption
and obesity, even among some low-income populations.
What Is the Issue?
Past research finds that the Food Stamp Program increases food expenditures and stabilizes incomes
of the poor. Yet, critics of the program have suggested that the program is too successful—that it has
unintentionally contributed to higher rates of obesity among some low-income populations. Recently
published studies that have explored the link between participation in the Food Stamp Program and
body weight have come to varying conclusions. This report reviews the findings of this emerging
body of work and discusses policy implications.
What Did the Study Find?
Results from the reviewed studies indicate that for the majority of program participants—children,
nonelderly men, and the elderly—use of food stamp benefits does not increase either Body Mass
Index (BMI) or the likelihood of being overweight or obese. For some subgroups, food stamp participation
has a negative association with the probability of overweight.
Nonelderly adult women, who account for 28 percent of the food stamp caseload, are the only
group of food stamp recipients for whom multiple studies show a link between food stamp receipt
and elevated BMI and obesity. According to these studies, food stamp participation over a 1- or 2-
year period increases the probability of a woman’s becoming obese by 2 to 5 percentage points and
may lead to a 0.5-point increase in BMI, or about 3 pounds for a woman 5’4” to 5’6” tall.
The length of time one participates in the Food Stamp Program may have an impact on obesity. The
reviewed studies found that long-term participation among nonelderly women was linked to a higher
probability of obesity by 4.5 to 10 percentage points. One study also found a smaller, but positive
relationship between long-term food stamp participation and obesity for men. These results may
suggest that small changes in BMI due to food stamp use accumulate over longer “spells” of participation.
But enough is not known about the causal mechanisms of participation and weight gain to
conclude that long-term use of food stamp benefits causes weight gain. Long-term food stamp participants
are likely to be different from short- and medium-term participants in ways that one cannot
observe.
It is also unclear why food stamp participation may affect women, but not men or children. Factors that may account
for this effect include differences in energy requirements, activity levels, or household allocation of resources.
Some evidence indicates that food stamp participation, food insecurity, and weight status are related. One study shows
that weight change over a 2-year period among women who were persistently food insecure was less than that for
women who were persistently food secure. But, food stamp participation roughly offset the smaller weight change for
those who were persistently food insecure—a result consistent with the program’s serving as a nutritional buffer during
difficult economic times.
The reviewed studies were faced with separating and measuring two distinct relationships. On the one hand, food stamp
participation may result in obesity. On the other hand, individuals who are heavier may be the very people who are
more likely to apply for food stamps, because of larger appetites, for example. Causal attribution is a major challenge for
these studies. Methodological and data weaknesses limit the ability of analysts to be certain that increased BMI and obesity
risk are due to food stamp participation. Differential effects across sex and age groupings are also unexplained.
The Food Stamp Program is a household-level program, and 89 percent of food stamp benefits go to households that
contain a child, elderly adult, or nonelderly disabled adult. Devising program changes that are appropriately targeted to
household members who may be at risk of gaining weight, without harming those who are not and who need the nutritional
assistance, presents a difficult challenge. Policy changes that help improve overall diets of all household members
may be more effective.
How Was the Study Conducted?
ERS reviewed studies that explored the link between food stamp participation and weight status. Particular attention
was given to studies that used multivariate analysis, longitudinal data, and accounted for self-selection bias. Results
are summarized by population subgroup: children (who make up the majority of food stamp participants), nonelderly
adult women, nonelderly adult men, and the elderly.
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