When the “healthy = sustainable” heuristic breaks down: the moderating role of familiarity for novel insect-based foods

Insect-based foods (IBFs) are frequently promoted as a sustainable protein alternative, but their market success hinges on consumer perception, which is often guided by cognitive heuristics. This research investigates the healthy = sustainable heuristic (HSH)—the intuitive belief that healthy foods are sustainable and vice versa—in the context of familiar and unfamiliar foods. Through three studies, we demonstrate that this heuristic is contingent on product familiarity. Study 1 (N = 220) found that while insect-based foods were perceived as moderately sustainable, the positive link between a health-oriented consumption focus and perceived sustainability held only for familiar foods (b = 5.74, p < .001) but was absent for unfamiliar ones (b = 0.45, p = .824)—a pattern consistent with the heuristic operating only where established food schemas exist. Study 2 (N = 96) showed that directly familiarizing participants with a cricket-based snack through tasting produced moderate improvements in sensory acceptance and health perceptions (r = 0.31, p = .011) but left sustainability perceptions unchanged (r = 0.14, p = .250)—suggesting that sensory experience alone does not integrate sustainability into consumers' evaluative framework. Study 3 (N = 187) revealed that for unfamiliar insect-based foods, an explicit sustainability prime boosted both sustainability (d = 0.43, p = .036) and health perceptions (d = 0.60, p = .009), activating the heuristic and leading to more favorable product attitudes through dual mediation. For familiar foods, the prime had no effect (ds = 0.02–0.09, ps > 0.64). We conclude that the HSH is a familiarity-contingent heuristic: for novel foods, the sustainability benefit is not intuitively inferred but must be explicitly communicated to trigger the heuristic and its positive spillover onto health perception and consumer attitudes.