Well-being has become a key concept in the context of food studies, whereas food insecurity, as its deprivation, has become an issue that requires political commitment. These two academic traditions, although having been developed somewhat independently, can be connected by using Amartya Sen’s capability approach. In this study, we applied the Alkire-Foster multidimensional poverty/well-being measurement method, which was theoretically informed by the capability approach, to develop a new method for measuring the quality of dietary life in high-income societies. The data were obtained from a web-based questionnaire conducted with the Japanese population (n = 973). Our demonstration identified about 40% of the population as having high food capabilities to lead one's valuable dietary life, as well as about 20% of the population as living under food poverty. The results also showed that socioeconomic status (SES) was correlated with food poverty, but not with eating well, and that gender- and age-based inequalities in food capabilities were larger than SES ones. We also discussed fundamental issues relevant to this measurement, including the lack of social consensus about the quality of dietary life, the complex relationship between dietary.