This study examined the relationship between food insecurity and obesity
and the mechanisms through which food insecurity might lead to obesity in
a sample of 436 healthy adult women from rural upstate New York.
The study had a prospective cohort design and women were followed from
early pregnancy until 2 years postpartum. Data were collected through self-administered behavioral questionnaires, food frequencies, and a medical
record audit. Height and weight measurements at all time points were
measured by healthcare providers following standardized study protocols.
Study results indicated that food insecurity at the beginning of pregnancy
was positively associated with major weight retention at 2 years postpartum,
but only in initially obese women (at a marginal significance level of
0.007). Initial obesity was also associated with increased risk of becoming
food insecure (at a marginal significance level of less than 0.05). Measures
of quantity of food intake, dietary quality, eating patterns, and physical
activity were examined as potential mediators. Consuming fewer than three
fruits and vegetables per day and a more binge-like pattern of eating were
associated with initial food insecurity and major weight retention at 2 years
postpartum (at a marginal significance level of less than 0.05). When these
variables were added to the regression model they did not reduce the coefficient
for food insecurity, a final criterion for being a mediating variable.
Obesity during early pregnancy was associated with increased risk of
becoming food insecure. The cross-lagged panel analysis indicated that this
causal direction was statistically significant when controlling for initial food
insecurity and weight status, while the other was not. This result provides
support for what can be described as ""reverse causality."" Thus, the previous
findings from cross-sectional studies of an association between food insecurity
and obesity may be due to the fact that obese women are at increased
risk of becoming food insecure over time.
Overall, no variables emerged as obvious mediators of the relationship
between initial food insecurity and major weight gain or change in food
security status (particularly becoming food insecure) and major weight gain.
The small sample sizes and the large variation of some of the variables may
have contributed to the lack of significant findings related to the mediators.
There are several other potential explanations for the study findings. One is
the possible timing of the measurement of the mediating variables. They
were measured over a year after the initial food insecurity measurement was
taken and this time period included a pregnancy. Additional data indicate
that all women's diets were similar during pregnancy regardless of their
initial food insecurity status. Seventy percent of food-insecure women
participated in the Special Supplemental Nutrition Program for Women,
Infants, and Children (WIC) during pregnancy. The additional food from
this program may have blunted any impact of food insecurity on eating
during pregnancy and this effect may have carried over into the postpartum
period, although the data clearly indicate that the initially food-insecure
women ate differently at 1 year postpartum than did food-secure women.
The dietary variables were measured a year before the weight measurement
was taken and it may be that change in diet related to weight change took
place closer to 2 years postpartum.
Women who were initially food insecure and were also obese formed a
distinct subgroup especially vulnerable to weight gain. This is a group that
may merit targeting for special intervention in food assistance programs.
Development and implementation of approaches to secondary prevention, in
the context of WIC, which is generally oriented toward primary prevention,
would require careful consideration of the length of postpartum participation
allowed, the composition of the WIC food package, and the focus and
content of nutrition education.