Humanity exceeds or threatens to exceed the planetary boundaries. The problem of unsustainable lifestyles in affluent contexts is, therefore, increasingly up for debate. Despite growing attention, this theoretical article argues that there is, in science as well as policy, a lack of recognition of the problem of unsustainable volumes of consumption, and institutional failure to address radical lifestyle change. While there is broad consensus about the societal need to address consumption patterns, controversies remain about the need to address the volumes of consumption. The article takes this debate as a point of departure and focuses specifically on a tendency in critical consumption studies within sociology and related disciplines: the neglect of the larger transformative potential embedded in lifestyle change at the grassroot level. It contributes with six arguments for why it is necessary to consider individual lifestyle changes, and particularly consumption reduction, as an active part of the greater transformation needed to make our societies fit within the planetary boundaries. It also contributes by highlighting five critical aspects on how such bottom-up change can contribute to transformative change. It thus contributes to the sociological and interdisciplinary theoretical, empirical, and normative discussion around the interplay between lifestyle change and sustainability transformation.