Recent trends in food insecurity in the United States parallel population increases in obesity. Historically, food insecurity and obesity have been viewed as distinct public health issues. However, since the mid-1990s, there has been growing interest in understanding the seemingly paradoxical relationship between these two issues. In this paper, the authors summarize findings from research examining associations between poverty, food insecurity, and obesity in the United States and propose a conceptual framework to characterize the factors that may foster a cycle of mutual influence among obesity, food insecurity, and their shared mechanisms and health-related outcomes.