The boundary model, proposed by Herman and Polivy in 1984, aims to explain why restrained eating often leads to unsuccessful dieting and, potentially, obesity. The model introduces the concept of the disinhibition of restraint, also known as the 'what the hell' effect. This occurs when a person surpasses their self-imposed dietary limits, often triggered by emotional distress, intoxication, or pre-loading (eating something considered fattening), and as a result, they continue eating more than usual.
Herman and Polivy also suggest that restrained eaters have a broader zone of biological indifference. This means they feel hungry more easily and take longer to feel full. According to their model, individuals on a diet set a cognitive diet boundary, limiting what they can eat. Once this boundary is crossed, for example, by eating chocolate, the 'what the hell effect' kicks in, causing them to continue eating until they reach their physiological boundary, which is higher than for non-restrained eaters.