The box office this summer (like most years, come to think of it) was jam-packed with action movies, from “Guardians of the Galaxy,” and “Hercules,” to “The Amazing Spider-Man 2.” But before you jump to On Demand to see all the flicks you missed in theaters or cue up Netflix to get a good adrenaline rush from one of your favorites, beware. All those captivating fight scenes might be making you gain weight. Seriously.

September 2014 study published in JAMA Internal Medicine found that TV-watchers snacked more while watching an action film as opposed to an interview program. Aner Tal, Ph.D., of Cornell University, and his colleagues, randomly assigned subjects to watch 20 minutes of TV—either an excerpt from the action movie “The Island,” the interview program “Charlie Rose,” or the same excerpt from “The Island” but without any sound. They also provided snacks: M&Ms, cookies, carrots and grapes, which were weighed before and after the screening.

They found that viewers watching the intense and distracting program, with frequent camera angle changes and variations in sound, ate 98 percent more grams of food and 65 percent more calories than the viewers watching the mundane interview program. Even the subjects who viewed the silent version of the action movie ate more—36 percent more grams and 46 percent more calories—than those watching “Charlie Rose.”

Mindless eating in front of the tube has been associated with weight gain for a while, but this is the first time we’ve been told that the actual content we’re watching can make a difference.So when you’re settling onto the sofa to watch the next action-packed movie, resist the urge to plop a family size bag of peanut M&Ms next to you. It’s impossible to focus on what you’re eating when you’re busy watching Spider-Man kick butt, so focus on it before you’re in action-induced trance to avoid a two-hour bottomless binge.