Observational satiety: watching yourself eat induces more fullness than watching another

Appetite is shaped not only by physiological need but by the sensory experience of eating and its social context. Can watching food being eaten itself induce satiety, and does it matter who is seen eating? In a functional MRI study (N = 41), participants watched videos of a wanted snack being eaten from their own perspective (self) or, using identical footage shown vertically inverted, as another's (other), holding food identity and visual content constant so that only the attributed agent varied. Observed eating reduced wanting, but not liking, for the eaten foods, whether one's own or another's; crucially, reported fullness increased only when the eating was seen as one's own. In the brain, food-value regions responded to watching eating in both conditions, a shared signal that strengthened over time. Yet only self-attributed eating engaged a self-specific, value-related response in the ventral striatum and medial prefrontal cortex, and orbitofrontal activity during self-eating scaled with each person's reported satiety, whereas watching another eat instead engaged the temporoparietal mentalizing network without a comparable rise in fullness. A large online survey (N = 1,000; ages 15-97) reproduced the behavioral effect across the adult lifespan, and a real-eating experiment reproduced its sensory-specific pattern. Watching eating, and whose eating it is, can thus recalibrate appetite through separate food-value and social-cognitive routes. This "observational satiety" offers a non-invasive route to study food wanting, of potential relevance to social eating and to today's food-media environments.