The Effects of Food Stamps on Obesity
ABSTRACT Poverty has historically been associated with a decrease in food consumption. This at least partially changed in 1964 when the Food Stamp Act began guaranteeing food for those in poverty. Since the act’s passage, the prevalence of obesity has increased dramatically, particularly among those with low incomes. This article examines the effects of the Food Stamp Program on the prevalence of obesity using 1979 National Longitudinal Survey of Youth data. Results indicate that food stamps have significant positive effects on obesity and the obesity gap for females, but these effects are relatively small, and consequently, such benefits are approximated to have played a minor role in increasing obesity at the aggregate level.
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ABSTRACT: The high prevalence of obesity among low income groups has led some to question the role of food assistance programs in contributing to the problem. The USDA's Food Stamp Program (now known as the Supplemental Nutrition Assistance Program – SNAP) is the largest food assistance program in the United States with over 40 million participants. This paper employed systematic realist review methods to determine whether participation in the Food Stamp Program causes obesity and the causal pathways through which this relationship may exist. Findings indicate a more consistent positive relationship for women than for men, especially for women who are long term users of the program. All studies discussed the ''food stamp cycle'' and an ''income effect'' as explanations for the role of food stamps in increased obesity yet evidence for these factors is limited. Curiously, the research in this field does not address obesogenic environments and we suggest that the absence of an understanding of household behavior in local contexts is a significant impediment to the reform of the Food Stamp Program.
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ABSTRACT: Bayesian analysis is given of an instrumental variable model that allows for t-distributed errors in both the structural equation and the instrument equation. Specifically, the approach for dealing with t-distributed errors is extended to the Bayesian instrumental variable estimator by modelling the variance for each error using a Gamma distributed hierarchical prior. The computation is carried out by using a Markov chain Monte Carlo sampling algorithm for the heteroskedastic case. An example using data illustrates the approach and shows that ignoring the presence of error terms with heavy tails in the instrument equation when it exists may lead to biased estimates.
DEPARTMENT OF ECONOMICS AND FINANCE WORKING PAPER SERIES • February 2010
The Effects of Food Stamps on
Charles L. Baum II *
Middle Tennessee State University, Murfreesboro, TN
Poverty has historically been associated with a decrease in food consumption. This at least partially
changed in 1964 when the Food Stamp Act began guaranteeing food for those in poverty. Since the Act’s
passage, the prevalence of obesity has increased dramatically, particularly among those with low incomes.
This paper examines the effects of the Food Stamp Program on the prevalence of obesity using 1979
National Longitudinal Survey of Youth data. Results indicate food stamps have significant positive effects
on obesity and the obesity gap for females, but these effects are relatively small and such benefits,
consequently, are approximated to have played a minor role in increasing obesity at the aggregate level.
Key words: Food stamps; weight; obesity; BMI
JEL category: I18
*Charles L. Baum II, Associate Professor Department of Economics and Finance, Middle Tennessee State
University, Murfreesboro, TN 37132, phone: 615-898-2527, fax: 615-898-5596, email: email@example.com.
This project was supported with a grant from the U.S. Department of Agriculture, Economic Research
Service (ERS). The opinions and conclusions expressed are solely those of the author and should not be
construed as representing the opinions or policy of any agency of the federal government.
An increasing number of Americans are obese, where obese is defined as having a body
mass index (BMI) of 30 or more and where BMI equals weight in kilograms divided by height in
meters squared (CDC 2006a). In fact, the latest estimates indicate that about 30 % of adult
Americans are currently obese, which is roughly a 100 % increase from 25 years ago (Flegal et al.
1998; Flegal et al. 2002; Ogden et al. 2006). These increases are found for both males and females,
as well as for various races. As a result of this dramatic, adult Americans are now more likely to be
obese than to smoke cigarettes.
Public health officials in the United States have become increasingly alarmed about the
growing prevalence of obesity because the medical literature finds that obesity increases morbidity
and mortality (Stevens et al. 1998; Calle et al. 1999) by increasing the prevalence of diabetes,
cardiovascular disease, stroke, cancer, hypertension, dyslipidemia, gout, sleep apnea, and
osteoarthritis (Must et al. 1999; Chow et al. 2000; Rauscher 2000; Castro-Rodriguez et al. 2001; Field
2001; Michaud et al. 2001; Kenchaiah et al. 2002). Some have asserted that obesity will soon
overtake tobacco as the leading preventable cause of death (Mokdad et al. 2004). Currently,
estimates suggest that obesity contributes to between 111,909 and 365,000 premature adult deaths in
the U.S. each year compared to 435,000 premature deaths due to tobacco (Allison et al. 1999;
Mokdad et al. 2004; Flegal, et al. 2005; Mokdad 2005).
Many societal changes do not initially appear to explain why the prevalence of obesity is
increasing. For example, an increasing portion of Americans are exercising and dieting, and
Americans are estimated to spend over 30 billion dollars on weight loss programs annually (Philipson
and Posner 1999). Furthermore, Americans currently possess more knowledge of the consequences
of obesity than ever before (Philipson and Posner 1999; Philipson 2001). Yet, Americans are more
likely to be obese now than ever.
Economists have examined various causes of obesity. For example, Philipson (2001),
Philipson and Posner (1999), and Lakdawalla and Philipson (2002, 2007) suggest that increased
obesity is the result of jobs becoming more sedentary; Anderson, Butcher, and Levine (2003) find
evidence that maternal employment increases childhood obesity because working mothers have less
time to prepare healthy meals; Cutler, Glaeser, and Shapiro (2003) assert that technological advances
in food preparation making food readily available have caused hyperbolic consumers (defined as
those who lack self-control) to overeat; and Chou, Grossman, and Safer (2004) find that BMI and
obesity have significantly increased due to increases in the number of restaurants and decreases in
I examine the effect of the Food Stamp Program on obesity. Prior to the Food Stamp Act
of 1964 (and other food assistance programs passed during the twentieth century), poverty was
assumed to be associated with a decrease in food consumption. Various twentieth century
government programs changed this by constructing a safety net that helps prevent those in poverty
from starvation. The Food Stamp Act does this by guaranteeing an allotment of food for those below
the poverty level (USDA 2003). In 2005, Food Stamp Program participants averaged $92.70 in
monthly benefits at a cost of $31.0 billion to the government (USDA 2006a). It is in the period since
the Food Stamp Act’s passage that the prevalence of obesity has increased so dramatically. Between
1971 and 1974, the Food Stamp Program served between 9.3 and 12.8 million participants annually
(USDA 2006a), and the prevalence of obesity in the United States was 14.5 % (Flegal et al. 2002).
These statistics have doubled. In 2005, the Food Stamp Program served an estimated 25.7 million
participants (USDA, 2006a), and the prevalence of obesity is currently over 30 %.
The Food Stamp Program potentially increases obesity by increasing food consumption,
resulting in excessive caloric intake. Food stamps potentially increase food consumption by making
the monetary cost of food zero for eligible individuals up to their food stamp allotment (though since
Food Stamp Program participation rates are well below 100 %, non-monetary costs such as stigma
and the opportunity cost of applying and re-certifying for the benefits likely remain significant). A
survey of the literature suggests a dollar of food stamps increases food consumption between $0.17
and $0.47, which is more than an equivalent amount of cash would (Fraker 1990). It is not surprising
that this would be true for constrained households, but this also appears to be true for the other 85 to
95 % of food stamp households that are unconstrained (Fraker 1990).
Although recipients could potentially use food stamps to buy healthier foods, recent
evidence by Wilde, McNamara, and Ranney (1999) suggests food stamp recipients consume
significantly more sugar and fat than eligible non-recipients. Additional evidence by Whitmore
(2002) indicates that food stamp recipients in San Diego and Alabama in the 1990s consumed more
soft drinks than peers who instead received cash benefits. If so, then it is possible that recipients not
only consume more food, they consume more of the foods likely to lead to weight gain.
Food stamps might also exacerbate obesity by promoting binge eating. Townsend et al.
(2001) suggest that abundant food at the beginning of each monthly food stamp cycle leads to over-
eating, with food becoming scarce at the end of each cycle. They argue that the net effect of this
cycle is weight gain. However, Townsend and colleagues also note that food insecurity and Food
Stamp Program participation are related.1 Food stamps could affect obesity by affecting (reducing)
food insecurity; alternatively, those who are food insecure could be more likely to apply for and
receive food stamp benefits, in which case food stamps and obesity would at least partially be
correlated with each other through a third, potentially unmeasurable, factor (food insecurity).2
Only a couple of studies have examined the effects of Food Stamp Program participation
on obesity. In the nutrition literature, seminal work by Gibson first examined this link.3 Gibson
(2003) finds that Food Stamp Program participation among low-income women (but not men) is
significantly associated with increased obesity. In concurrence, economists Meyerhoefer and
Pylypchuk (2008) find that contemporaneously-measured food stamp receipt has statistically
significant positive effects on low-income women but not on low-income men.
In this project, I estimate the relationship between food stamp benefits and the probability
of being obese and the obesity gap (which is the prevalence of obesity multiplied by the average
amount by which BMI exceeds the obesity threshold) with National Longitudinal Survey of Youth
(NLSY79) data. I focus the analysis on sub-samples of income-eligible males and females and
control for possible omitted variable bias using an individual-specific fixed effects estimator. I
attempt to build on Gibson’s (2003) and Meyerhoefer and Pylypchuk’s (2008) work by exploring the
dynamic relationship between food stamps and obesity where current weight is linked to past weight
and past food stamp receipt. This seems like an important area for research because
contemporaneously-measured food stamp receipt would not be expected to have an instantaneous and
substantial effect on weight. Instead, since current weight is not independent from past weight, the
food stamp-weight relationship is likely much more complex. To do this, I estimate (i) models that
explain weight changes over time with controls for initial weight status, (ii) models that identify the
effects of current and past program receipt to explore whether food stamps have lagged effects, (iii)
models that identify the effects of patterns of food stamp receipt, including short-term, medium-term,
and long-term receipt, as well as the effects of receiving benefits in multiple spells, and (iv) models
that explain the hazard rates for becoming obese at particular times during a 15-year period
conditional on not yet being obese.