With nearly 40% of global mortality attributable to dietary factors, citizens are encouraged to eat more healthily. But how do people conceptualize healthy foods—and how is this conceptualization embedded in their cognitive representations of food ecology? Adolescents, lay adults, and nutritional experts rated a large, heterogeneous set of food products on a diverse set of characteristics, and we applied the psychometric paradigm pioneered in risk-perception research to identify the dimensions structuring the cognitive representations of those foods. We then used the foods’ scores on these dimensions to predict respondents’ judgments of the healthiness of those foods. Animal-based nutrients (eg, cholesterol, fat, protein) and naturalness levels (eg, processing, artificial additives) were the two central dimensions structuring respondent representations of the foods. Relative to the other two groups, the adolescents’ representations were less differentiated. Perceived healthiness was determined by multiple factors, but its strongest predictor was a food’s naturalness. These structures emerged for all respondent groups, but there was a high degree of variability among the adolescents.