The boundary model was proposed by Herman and Polivy (1984) to explain how restrained eating can lead to unsuccessful dieting (and potentially obesity). It suggests that many diets fail due to the disinhibition of restraint effect (also known as the ‘what the hell’ effect). This is where a person passes through their self-imposed restraint, often in response to emotional distress, intoxication or pre-loading (eating something considered to be fattening), and therefore continues to eat more than they usually would. Herman and Policy also claim that restrained eaters have a larger zone of biological indifference, which means they feel hungry more easily and then take longer to feel full. It is claimed that dieters set themselves a cognitive diet boundary, which limits what they can eat. If they ever cross this boundary (e.g. eating chocolate) the ‘what the hell effect’ kicks in and they will then continue to eat until they are full and reach their physiological boundary, which is higher than for non-retrained eaters.