Watching a horror movie could burn off 200 calories or a whole bar of chocolate, according to new research released.
Viewers who put themselves through 90 minutes of adrenaline-pumping horror movie terror can use up as much as 113 calories, close to the amount burned during a half-hour walk and the equivalent to a chocolate bar.
The movie top of the list of calorie-burners was found to be the 1980 psychological thriller The Shining, with the average viewer using up a whopping 184 calories.
Jaws took the runner-up spot, with viewers burning on average 161 calories, and The Exorcist came third, with 158 calories.
The University of Westminster study measured the total energy expenditure of ten different people as they watched a selection of frightening movies.
Scientists recorded their heart rate, oxygen intake and carbon dioxide output - and discovered the number of calories used increased by on average a third during the films.
The research also revealed films featuring moments designed to make viewers jump in terror are the best calorie-burners, as they cause heart rates to soar.
Dr Richard Mackenzie, senior lecturer and specialist in cell metabolism and physiology at the University of Westminster, said: "Each of the ten films tested set pulses racing, sparking an increase in the heart rate of the case studies.
"As the pulse quickens and blood pumps around the body faster, the body experiences a surge in adrenaline.
"It is this release of fast acting adrenaline, produced during short bursts of intense stress (or in this case, brought on by fear), which is known to lower the appetite, increase the Basal Metabolic Rate and ultimately burn a higher level of calories."
Helen Cowley, editor of the movie rental company LOVEFiLM - which commissioned the University of Westminster study - said: "We all know the feeling of wanting to hide behind the sofa or grab a pillow when watching scary or hair raising scenes, but this research suggests that maybe those seeking to burn some calories should keep their eyes on the screen."
The top 10 calorie-burning frightening films were:
1. The Shining: 184 calories
2. Jaws: 161 calories
3. The Exorcist: 158 calories
4. Alien: 152 calories
5. Saw: 133 calories
6. A Nightmare on Elm Street: 118 calories
7. Paranormal Activity: 111 calories
8. The Blair Witch Project: 105 calories
9. The Texas Chain Saw Massacre: 107 calories
10. [Rec]: 101 calories