Consumers Underestimate Calories in Fast-Food Meals; Teens Do So by as Much as 34 Percent

    • May 23, 2013

Princeton, NJ — Diners at fast-food restaurants in New England significantly underestimate the number of calories in their meals, according to a study published today in BMJ, a journal of the British Medical Association. The study found that teens underestimated the most, believing that their orders had about one-third fewer calories than the meals actually contained. Other research published earlier this month shows that diners buy meals with fewer calories when using calorie labels on in-store menus or menu boards at chain restaurants.

The study published today, “Consumers’ Estimation of Calorie Content at Fast Food Restaurants” is the first large-scale effort to examine the difference between the estimated and actual calorie content of foods purchased by adults, teens, and children at fast-food restaurants. It was funded by the Robert Wood Johnson Foundation (RWJF) through its Healthy Eating Research program, as well as other funders, including the RWJF Health and Society Scholars program. It was conducted by the Harvard Medical School/Harvard Pilgrim Health Care Institute in conjunction with leaders of the Massachusetts and Connecticut Departments of Public Health.  

“We found that people, especially teens, are consuming more calories than they think they’re getting when they eat fast food,” said lead researcher Jason Block, MD, MPH, of the Harvard Medical School/Harvard Pilgrim Health Care Institute. “Teens underestimate the number of calories in their meals by as much as 34 percent, parents of school-age children by as much as 23 percent, and adults by as much as 20 percent.” Block and colleagues surveyed nearly 3,400 adults, teens, and school-age children in 2010 and 2011 at 89 fast-food restaurants in four New England cities.

The researchers found adults ordered meals containing 836 calories on average, but typically underestimated the calorie content of those meals by 175 calories. Teens had the largest gap—they underestimated the number of calories in their average order, which contained 756 calories, by 259 calories. Parents of school-age children underestimated their orders, which contained an average of 733 calories, by 175 calories overall. Notably, one-quarter of all participants underestimated the calorie content of their meals by at least 500 calories.   

“We also saw differences by food chain,” said Block. Subway patrons underestimated the number of calories in their orders by a larger amount than did patrons of McDonald’s, Burger King, KFC, Wendy’s, and Dunkin’ Donuts. Compared with McDonald’s patrons, estimates provided by adults and teens who ate at Subway were 20 percent and 25 percent less accurate, respectively. Block suggested that Subway’s branding may provide a “health halo” among the public.    

“These findings tell us that many people who eat at fast-food restaurants may not be making informed choices because they don’t know how many calories they’re consuming,” said Block. “Having the information is an important first step for anyone wanting to make changes.” At the time of Block’s study, none of the chains his team analyzed routinely posted calorie information on their menus. 

 Menu Labeling Prompts Customers to Buy Fewer Calories at Chain Restaurants

Another study released this month shows that adults and teens who used calorie information posted on menus or menu boards in Seattle-area (King County, WA) chain restaurants purchased up to 143 fewer calories than customers who did not see or use the calorie information.

The study, also supported by the Robert Wood Johnson Foundation through its Healthy Eating Research program, was published in the American Journal of Preventive Medicine. It evaluated the impact of King County, Washington’s menu-labeling regulation six and 18 months after it went into effect. The study, “Menu Labeling Regulations and Calories Purchased at Chain Restaurants” is the first to examine the impact of a menu-labeling mandate more than one year after implementation.

In 2009, King County became the second jurisdiction in the nation to implement a menu-labeling law. Eighteen months later, researchers found the average calories per purchase at chain restaurants fell by 38 calories, from 908.5 calories to 870.4, regardless of whether customers reported seeing or using the calorie information. One-third of customers reported using calorie information to guide their purchases and the impact was greatest among this group—an average decrease of 143 calories per purchase.

Researchers surveyed more than 7,300 patrons ages 14 and older at 10 restaurant chains, including Subway, McDonalds, Taco Bell, Starbucks, and other local chain restaurants before the law took effect, and again six and 18 months after implementation. They found no significant changes in purchase patterns six months after the menu labeling law took effect, but found a modest, meaningful decrease in the number of calories per purchase after 18 months.

“Menu labeling is critical because Americans spend nearly half of their food dollars on foods prepared outside the home, which tend to be higher in calories and less healthy than what we eat at home,” said researcher James W. Krieger, MD, MPH, with Public Health–Seattle & King County. “Over time, people seem to respond to the availability of information and use it to inform their purchases.”

As required in the Patient Protection and Affordable Care Act of 2010, the U.S. Food and Drug Administration is expected to publish final regulations mandating that chain restaurants—defined as those operating at least 20 locations—post calorie information on menus alongside price and provide additional information, such as the total amount of fat, sodium, and cholesterol, upon customer request. 

Media Contact:
Christine Clayton | Robert Wood Johnson Foundation | | (609) 627-5937


About Robert Wood Johnson Foundation

The Robert Wood Johnson Foundation focuses on the pressing health and health care issues facing our country. As the nation's largest philanthropy devoted exclusively to health and health care, the Foundation works with a diverse group of organizations and individuals to identify solutions and achieve comprehensive, measureable, and timely change. For 40 years the Foundation has brought experience, commitment, and a rigorous, balanced approach to the problems that affect the health and health care of those it serves. When it comes to helping Americans lead healthier lives and get the care they need, the Foundation expects to make a difference in your lifetime. For more information, visit Follow the Foundation on Twitter or Facebook


About Healthy Eating Research

Healthy Eating Research is a national program of the Robert Wood Johnson Foundation (RWJF). The program supports research on environmental and policy strategies with strong potential to promote healthy eating among children to prevent obesity, especially among lower-income and racial and ethnic populations at highest risk for obesity. For more information, visit