When was the last time you scarfed down three quarter-pounder cheeseburgers slathered in 12 pats of butter?

As horrifying as it may seem, for Americans, it was likely the last time they were at the movies.

That's because a new laboratory analysis, commissioned by the Washington-based Center for Science in the Public Interest, suggests the burger scenario is the nutritional equivalent of one medium bag of movie popcorn, washed down with sugary pop.

The tests were done on a $12 popcorn combo served at Regal, the largest movie theatre chain in the United States. The combo added up to a whopping 1,610 calories and 60 grams of saturated fat, which nutritionists say is about three days worth of fat intake.

"Who expects about 1,500 calories and three days' worth of heart-stopping fat in a popcorn and soda combo? That's the saturated fat of a stick of butter and the calories of two sticks of butter," said Jayne Hurley, the organization's senior nutritionist, in a news release.

"You might think you're getting Bambi, but you're really getting Godzilla."

For Canadians, the results aren't a whole lot better — about three quarter-pounder cheeseburgers, but without the added butter.

The large popcorns sold at Cineplex, the largest cinema chain in the country, contain 1,120 calories, five grams of saturated fats, and 530 milligrams of sodium. Putting butter on top adds another 22 grams of fat and 320 calories.

AMC's large popped snacks, which are made in coconut oil, have 940 calories, a whopping 38 grams of saturated fat, and 630 milligrams of sodium; the chain's "buttery topping" contributes another 310 calories and six grams of fat.

Empire's popcorn is by far the healthiest of the three national chains. But a large serving still packs 730 calories, three grams of saturated fats, and an unparalleled 1,480 milligrams of sodium.

Justin Scott, a spokesman for the Kansas City-based AMC Entertainment, said the company has introduced healthier alternatives at a number of theatres. When similar studies came out in the mid 1990s, "AMC responded by immediately testing several other oils and products," Scott said in an e-mail.

Coconut oil, which AMC uses, is about 90 per cent saturated — more than twice as saturated as lard, the study said.

"Our guests overwhelmingly rejected these products and let us know they preferred the flavour of our popcorn as it was," said Scott. "Ultimately, we are focused on our guests' movie-going experience in total, and it includes many choices as well as mainstays like popcorn and candy."

As for the other snacks sold at the movies, oversized boxes and bags of candy sold at movie chains are universally high in calories. For example, tests show a 355-gram pack of Maynards Swedish Berries contains 1,270 calories and 255 grams of sugar. For a 250-gram pack of Twizzlers, it's 830 calories and 103 grams of sugar.

The calories climb even higher in combo meals. At Cineplex, a large popcorn, a large beverage, and a 150-gram serving of M&Ms adds up to 2,320 calories and 24 grams of saturated fats.

Hurley said the lab analysis on AMC's popcorn, the serving sizes were consistently larger than advertised. So what AMC claimed to be a 225-calorie small popcorn was found to contain 330 calories; a 660-calorie large grew to 940 calories.

"Sitting through a two-hour movie isn't exactly like climbing Mt. Everest," Hurley said. "Why do theatres think they need to feed us like it is?"