Almost fifty million people are food insecure in the United States, which makes food insecurity one of the nation’s leading health and nutrition issues. We examine recent research evidence of the health consequences of food insecurity for children, nonsenior adults, and seniors in the United States. For context, we first provide an overview of how food insecurity is measured in the country, followed by a presentation of recent trends in the prevalence of food insecurity. Then we present a survey of selected recent research that examined the association between food insecurity and health outcomes. We show that the literature has consistently found food insecurity to be negatively associated with health. For example, after confounding risk factors were controlled for, studies found that food-insecure children are at least twice as likely to report being in fair or poor health and at least 1.4 times more likely to have asthma, compared to food-secure children; and food-insecure seniors have limitations in activities of daily living comparable to those of food-secure seniors fourteen years older. The Supplemental Nutrition Assistance Program (SNAP) substantially reduces the prevalence of food insecurity and thus is critical to reducing negative health outcomes.