Watching action films may make you more likely to pile on the pounds, according to US researchers.
Previous studies have suggested a link between television and obesity but the team at Cornell University tried to establish which genres of television were worst.
The findings, published in JAMA Internal Medicine, showed people snacked far more during action films.
The authors said people should avoid snacking while watching television.
TV is linked to obesity because of junk-food advertising, sedentary behaviour and distracting people so they do not realise how much they are eating.
The study followed 94 students who were given bowls of chocolate, biscuits, carrots or grapes while watching television.
The scientists then compared how much food was consumed during the 2005 action movie, The Island, with a show based on one-to-one interviews.
They demonstrated that people had nearly had twice the amount of food by weight and consumed 65% more calories during the film.
The difference was more pronounced in men than women.
The report says: "TV may lead distracted viewers to mindlessly eat past the point at which a person would usually stop.
"When counselling patients, physicians should stress the dangers of overeating while watching TV.
"[They] may want to warn in particular against the potential effect that highly distracting content, such as action movies, may have on overeating.
"When watching highly distracting TV content, it may be best to avoid snacking."