11 Jan 2010 --- As a growing number of fast food and chain restaurants display the calorie content of their dishes on websites and menus, a study suggests some of this information may be unreliable.

Researchers at Tufts University analyzed the calorie content of 18 side dishes and entrees from national sit-down chain restaurants, 11 side dishes and entrees from national fast food restaurants and 10 frozen meals purchased from supermarkets. They compared their results to the calorie content information provided to the public by the restaurants and food companies. "Because we analyzed a relatively small sample of food, additional research testing more foods will be needed to see if this is a nation-wide problem," says senior author Susan B. Roberts, PhD, a professor at the Friedman School of Nutrition Science and Policy at Tufts University.

On average, the calorie content information provided by the restaurants was 18 percent less than the researcher's calorie content analysis. Two side dishes exceeded the restaurant's reported calorie information by nearly 200 percent. The calorie content information reported by packaged food companies averaged 8 percent less than the researchers' analysis. "If people use published calorie contents for weight control, discrepancies of this magnitude could result in weight gain of many pounds a year," Roberts says.

Writing in the January issue of the Journal of the American Dietetic Association, the authors attribute the smaller 8 percent discrepancy between their results and the calorie content information from the frozen food companies to Food and Drug Administration (FDA) oversight of Nutrition Fact information labels. Current FDA rules are more lenient towards underreporting calories than over reporting them.

"We tested frozen foods straight out of their packages. For the restaurant foods we first calculated calorie content based on the portion we were served," Roberts says. "When we went one step further and calculated calorie content based on the portion size listed on the restaurant's nutrition literature, the discrepancies between our results and the restaurant's results decreased, which suggests oversized portions were part of the problem."

Five restaurants offered free side dishes which were not factored into the calorie information provided for the entrees. The authors observed that, on average, the side dishes contained more calories than the entrées they accompanied.

"Restaurant menus and websites should be as clear as possible," Roberts says. "For example, listing the calorie contents of free side dishes on separate pages from entrees may mislead customers about how much they are eating and may prevent them from making informed decisions between different side dish choices."

The authors also note recent municipal initiatives asking restaurants to publicize nutrition information. "If the goals of these polices are to encourage a healthier society and weight loss, inaccurate calorie content information could well hamper these efforts," Roberts says.

This work was supported by the National Institutes of Health (NIH) and the U.S. Department of Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.