Watching a horror film can burn the same amount of calories as spending an hour washing windows - and is infinitely more enjoyable.
Researchers at the University of Westminster monitored participants as they watched 10 classic scary flicks and found on average that they burned an average of 133 calories, the same as half a dairy milk bar.
Of the ten films, Stanley Kubrick's 'The Shining' burned the most calories - 184.
Dr Richard Mackenzie, who led the study, commissioned by Lovefilm, 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."
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 Texas Chain Saw Massacre: 107 calories
9. The Blair Witch Project: 105 calories
10. [Rec]: 101 calories