Warning women that eating chocolate can make them fat may actually drive some to eat more, research from the University of Western Australia (UWA) shows.
The joint study with the University of Strathclyde in Scotland found low restraint eaters - those not on a diet - showed a strong impulse to eat chocolate when presented with negative messaging, including warnings that chocolate could lead to obesity.
Women on a diet were also prone to rebel against attempts to scare them off chocolate, particularly by ads featuring thin models.
Researchers found dieters shown ads featuring thin models displayed an increased desire to eat chocolate coupled with greater feelings of wanting to avoid consumption, or indulged in higher consumption - and ultimately felt more guilt.
Lead author Professor Kevin Durkin said the reaction of a warning having a contrary effect was known as "reactance".
"Reactance could be more marked among the low-restraint participants because they are generally less preoccupied with regulating their food intake and thus find external attempts to intervene in freely determined behaviour more jarring," Prof Durkin said.
The study involved 80 female participants between the ages of 17 and 26, categorised into low or high restraint and scored on a specifically designed "chocolate questionnaire" developed by UWA-based psychologist Professor Werner Stritzke.
The research was published in the journal Appetite, which specialises in behavioural nutrition and the cultural, sensory, and physiological influences on intake of foods and drinks.