Do politically irrelevant events influence important policy opinions? Previous research on social welfare attitudes has emphasized the role of political factors such as economic self-interest and ideology. Here, we demonstrate that attitudes to social welfare are also influenced by short-term fluctuations in hunger. Using theories in evolutionary psychology, we predict that hungry individuals will be greedier and take more resources from others while also attempting to induce others to share by signaling cooperative intentions and expressing support for sharing, including evolutionarily novel forms of sharing such as social welfare. We test these predictions using self-reported hunger data as well as comparisons of subjects who participated in relevant online studies before and after eating lunch. Across four studies collected in two different welfare regimes—the United Kingdom and Denmark—we consistently find that hungry individuals act in a greedier manner but describe themselves as more cooperative and express greater support for social welfare.