Overall, the evidence on the impact of SNAP participation on food insecurity is moderately strong. While there have been no randomized controlled trials that can shed light on how SNAP affects household food insecurity, the nonexperimental studies reviewed have made serious efforts to account for the possibility of selection bias in their impact estimates. In particular, these studies have used various methods to account for observed and unobserved factors that lead some households to receive SNAP benefits and others not to participate.
The evidence suggests that food insecurity is common among SNAP participants. As discussed above, data from 2011 show that just under half of SNAP households (48 percent) were food secure, with 29 percent having low food security and 23 percent having very low food security. These rates of low and very low food security were nearly twice the rates for income-eligible households that did not participate in the program, 16 percent of which had low food security and 11 percent very low food security. Among higher-income households (those with incomes above 185 percent of the federal poverty threshold), more than 90 percent were food secure.6 Subgroups for which food insecurity is particularly prevalent include female-headed households with children and African American– and Hispanic-headed households (Coleman-Jensen et al., 2012a).
Although the prevalence of food insecurity is relatively high among SNAP participants, the most recent research suggests that it would be even higher absent SNAP benefits—in other words, that SNAP benefits have positive impacts on participants’ food security (i.e., reducing households’ likelihood of food insecurity). This finding raises the question of whether the high prevalence of food insecurity among SNAP households could be further reduced with higher benefit levels.
Taken together, the evidence suggests that SNAP benefits help alleviate food insecurity, but not enough to reduce the level of insecurity to that of either higher-income households or lower-income households that do not participate in the program. Evidence is less complete on the levels of food insecurity and impacts of benefits among subgroups of participants.
6These statistics are based on the 12-month measure of food insecurity and thus may be influenced by the households’ experiences prior to entering SNAP. The patterns of food insecurity based on the 30-day measure were similar to those reported here, although the food insecurity rates were somewhat lower (Coleman-Jensen et al., 2012a).