Field of Science


Everyone Underestimates Fast-Food Calories (But Especially at Subway)

At a McDonald's shareholder meeting last week, a nine-year-old girl accused CEO Don Thompson of sneaky advertising. Stop "tricking kids into eating your food," she demanded, saying that McDonald's ads tell kids to "keep bugging their parents" until they get that Happy Meal. In the world of fast-food chains, though, the golden arches may not be the sneakiest purveyor of excess calories. Diners in all kinds of fast-food restaurants underestimate the calories they're taking in—and the most dramatic underestimation happens at Subway.

Thompson may not have been swayed, but Jason Block of Harvard Medical School and a group of other researchers writing in BMJ do care what consumers think about their fast food. Specifically, they care how many calories people think they're eating. To find out, they went into the trenches: 80 fast-food restaurants in New England cities.

Researchers stood outside their chosen dining establishments (which included McDonald's, Burger King, Subway, Wendy's, KFC, and Dunkin' Donuts) in 2010 and 2011. They asked customers on their way in whether they'd be willing to save their receipts and answer a few questions when they came back out. (Only a few restaurants kicked the researchers off the premises.) At dinnertime, they targeted adults, either eating on their own or with kids. At lunchtime and after school let out, they went to fast-food places within a mile of a school and talked to adolescents.

In all, more than 3,000 people participated. Across all the restaurant chains, the average dinnertime meal for adults was 836 calories, and the average afternoon meal for adolescents was 756 calories. Yet when asked how many calories they thought their meals held, people consistently guessed too low. And the bigger their meals were, the more severely they underestimated.

The researchers also asked subjects whether they'd noticed any calorie information indoors. "All of [the chains] provide information in some way," says Block—"on a wall poster, on napkins/cups, on sandwich wrappers and tray liners, and on 'special menus' that might present items that are below a certain number of calories."

Yet less than a quarter of adults said they'd even noticed this information. Those people didn't do any better at estimating their calories than others. Did they use the information to help them make menu choices? Only five percent of all adults said yes. Of adolescents, two percent.

Block says it's easy for diners to miss the calorie information provided by fast-food chains today. But soon, as part of the Affordable Care Act, all chain restaurants with more than 20 locations will have to post calorie information in a standard format. "The menu labeling regulation will require the calories to be up front and highly recognizable," Block says.

Even this kind of prominent labeling has had mixed results in past studies. However, Block adds, the new law will also require menus to post an "anchoring statement" pointing out that people only need about 2000 calories a day. This might make, say, the 970 calories in a Wendy's Baconator more meaningful to a customer.

Anchoring was effective in at least one small study, Block says. Other studies have looked at "traffic light" labeling (in red, yellow, or green), or listing calories in terms of how much exercise you'd need to burn them back off. "We'll be in a position to know much more after the federal law is implemented," Block says. His group is collecting data this year and next year to see how well the new labeling works.

If people do start noticing how many calories their favorite chains are offering, they may be surprised. When researchers broke down their results by restaurant chain, they found that people underestimated their calories more dramatically at some restaurants than others. At McDonald's, adults guessed too low by an average of 100 calories, and adolescents by a little more than 200. The guesses were off by a bit more, on average, at Burger King and Wendy's. At Subway, the errors were most extreme: adults underestimated their calories by an average of about 350, adolescents by close to 500.

Five hundred calories is equivalent to all the bread in a 12-inch sub (or, if you opt for multigrain, all the bread plus four American-cheese triangles). It's a lot not to know you're eating. This mistake, the authors write, may happen because people view Subway with a "health halo." After seeing TV ads featuring fresh vegetables, smiling Olympians, and Jared's old pants, consumers may think they're making a healthier choice than they are.

The new calorie labeling could help most in places like this. A fast-food chain that brands itself as healthy is even sneakier than someplace like McDonald's, which even little girls know is bad for you.

Image: by Jeremy Brooks (via Flickr)

Block, J., Condon, S., Kleinman, K., Mullen, J., Linakis, S., Rifas-Shiman, S., & Gillman, M. (2013). Consumers' estimation of calorie content at fast food restaurants: cross sectional observational study BMJ, 346 (may23 3) DOI: 10.1136/bmj.f2907


  1. When I am shopping for fast food, I use calorie information to calculate maximum calories for the money.

  2. I know that when I get food at Domino's Pizza I'd like to know the calories and nutritional information for each of their approximately 34,000,000 food order combinations - or, approx. the same number of combinations of my "Obamano's Pizza" Slot Machine:

    BTW: If people aren't smart enough to realize that a larger portion of any food has more calories than a smaller portion of that same food, then all the Nutritional Statements in the world are not going to help them ;-)

    Thanks for reading!

  3. I use and the calorie counter app to get calorie counts. It's pretty good.

  4. All I know is I've lost 30 lbs so far this year focusing on switching from other fast foods and restaurant dining to turkey/bacon subs at Subway and Jimmy Johns

    1. You can get a 6 inch Subway Club with light vinegar and oil for around 350 calories or 9 Weight Watcher points. Why beat up on Subway just to gin up a good headline? The problem is that we have stupid, lazy people that don't exercise or take care of their bodies. But I guess that we now live in a commune means that someone has to watch over what the other guy eats.

  5. If people are this stupid then they deserve to be fat. So the nanny state is going to fix this? How many calories are there in the White House meals when Obama has Beyoncé over? How many calories are in the brie baguettes served on the upper East Side when all of the liberals have their fund raisers? Good grief. Aren't people responsible for their own bodies? Oh, that's right, they are not.

  6. The writing in this article is dishonest. "the golden arches may not be the sneakiest purveyor of excess calories" is misused as a lead-in to poor estimates by consumers, which is something completely different from willful misrepresentation by the company. Why not just report on the issue at hand honestly? Sheesh!

  7. then who are these sneaky purveyors? This article is misleading in several ways since the caloric information is visible on menus, available in print and online, for those interested. Providing an anchoring statement will no more reduce calories that people, in their own free will, choose to indulge.
    Its possible to eat at say, McDonalds or Subway, three meals and stay below 2000 calories.

  8. Activist Mother used her 9 year-old to parrot her political views at McDonald's shareholder convention. Who is in control, the child or parent. Don't eat fast food if you think it unfit.


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