London: Think twice before you plan to go on a diet. A new study has indicated that dieting may help you to shed your extra pounds but it may also be stressful and can make you feel irritable and angry.

Researchers have found that the effort involved in exerting self-control over eating can lead to an aggressive frame of my mind.

They have based their findings on an analysis of a set of three experiments.

In one experiment, people who choose an apple instead of a chocolate bar were more likely to choose movies with anger and revenge themes than milder or soft movies.

In another experiment, participants who exerted financial restraint by choosing a gift certificate for groceries over one for a spa service showed more interest in looking at angry faces rather than fearful ones.

In the third experiment, dieters had more favorable opinions toward a public policy message that used an anger-inducing appeal -- if funds are not increased for police training, more criminals will escape prison – than they did toward a sad message.

Finally, participants who chose a healthy snack over a tastier less-healthy one were more irritated by a marketer's message that came across as dictatorial, the findings revealed.

"We set out to examine whether exerting self - control can indeed lead to a wide range of angry behaviours and preferences subsequently, even in situations where such behaviours are quite subtle," said lead authors David Gal of Northwestern University.

Added co-author Wendy Liu of University of California: "Instead behavioural interventions might rely on a broader range of methods to foster positive behaviours toward long-term goals."

The findings have been published in the 'Journal of Consumer Research'.