Context Food insecurity disproportionately affects U.S. demographic groups of children and adult family members at the highest risk for obesity and may lead to weight gain through various pathways. This article reviews research regarding the relationship between food insecurity and weight status, and the potential role of federal food and nutrition assistance programs. Evidence acquisition A search for relevant peer-reviewed research studies among U.S. children and nonelderly adults, published between 2000 and March 2010, identified 42 studies regarding the relationship between food insecurity and weight status. There were 22 studies regarding the potential role of food and nutrition assistance programs. Evidence synthesis Among children and men, support for an association between food insecurity and weight status has been mixed. Women who experience food insecurity are more likely to be overweight or obese compared to women with adequate household resources for food; however, there is little evidence that food insecurity promotes increased weight gain over time. Long-term participation in the Supplemental Nutrition Assistance Program may increase risk for excess weight gain. Conclusions Additional research addressing the limitations of current studies is needed to fully understand the observed linkages between food insecurity and risk for obesity. Nevertheless, there is substantial evidence these nutritional problems coexist, and it is critical that future efforts to eliminate hunger consider opportunities to promote healthy food choices and physical activity. Evaluations of policy changes and other intervention strategies are needed to determine the potential for food and nutrition assistance programs to more effectively reduce obesity among participants.