If you have ever thought that getting into shape was terrifying work, then that's because it is.
According to research commissioned by Lovefilm, if you are keen to shed some pounds this Halloween all you have to do is sit on your sofa and watch a scary film.
Scientists at the University of Westminster claim that watching spooky classics such as The Exorcist in the comfort of your own home burns just as many calories as a 30-minute walk.
They measured the heart rate, oxygen intake and carbon dioxide output of 10 subjects while they watched a selection of frightening movies.
The study found that on average viewers burned 113 calories over 90 minutes and that films featuring heart-racing moments of terror are the best calorie-burners.
Dr Richard Mackenzie, senior lecturer and specialist in cell metabolism and physiology at the University of Westminster, explained that the scarier the picture the more optimum energy a viewer uses.
"Each of the 10 films tested set pulses racing, sparking an increase in the heart rate of the case studies," he told the Telegraph.
"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," he explained.
The 1980 psychological thriller, The Shining, came out on top as the best for calorie-busting. The average viewer watching the Jack Nicholson film burned up 184 calories.
Steven Spielberg's 1975 film Jaws came second with viewers burning on average 161 calories and the 1973 classic The Exorcist secured third place with 158 calories.
Lovefilm editor Helen Cowley 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-scaring 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