Research paper
de Castro JM. Family and friends produce greater social facilitation of food intake than other companions. Physiology & Behavior. 1994;56(3):445-450. doi:10.1016/0031-9384(94)90286-0. PMID: 7972393.
Why we cite it
Part of de Castro’s diary-study series on social context and meal size. These are correlational diary studies — people recorded what they ate and who they ate with — so they establish association, not cause. This study extends the earlier finding that meals with others are 44% larger (de Castro & de Castro 1989) by showing that the type of companion matters: family and friends produce even greater social facilitation than coworkers or acquaintances. The mechanism is twofold — social interaction extends meal duration (time extension hypothesis), and familiarity with companions produces relaxation and disinhibition of dietary restraint. For the project, this explains why weekends, holidays, and social gatherings reliably lead to overeating, and why awareness of this social effect is a key environmental factor.