BOSTON – Consumers can’t seem to accurately estimate the calorie content of their meals — especially large meals — at fast-food restaurants, according to a new study from researchers from the Harvard School of Public Health. The study was published May 23 in BMJ, a journal of the British Medical Association.

The study showed some portions of the population significantly underestimated the calories in their meals. The study involved surveys with approximately 3,400 adults, teenagers and school-age children who visited 89 fast-food restaurants in four cities in New England during 2010 and 2011.

The researchers found that at least two-thirds of all participants underestimated the calorie content of their meals, with about a quarter underestimating the calorie counter by at least 500 calories.

Adults ordered meals that contained an average of 836 calories but underestimated those meals by 175 calories, or about 20 percent. Teenagers ordered meals that contained an average of 756 calories but underestimated those meals by 259 calories, or 34 percent. School-age children ordered meals that contained an average of 733 calories but underestimated those meals by 175 calories, or 23 percent, the study said.

Of the restaurants visited — McDonald’s, Burger King, Subway, Wendy’s, KFC and Dunkin’ Donuts — the largest underestimation of calorie content for adults and teenagers occurred at Subway. The values were similar for all chains among school age children.

The researchers said that at the time of data collection none of the restaurant chains in the sample routinely printed calorie counts on menus. The chains presented calorie counts, along with additional nutrition information, on wall posters, food containers, napkins and cups or on limited menus identifying food choices with less than a specified number of calories.

Consumers did not necessarily notice the printed calorie information, though. The survey found only 22 percent of adults, 14 percent of teenagers and 15 percent of school-age children noticed calorie information in the restaurants, but only 5 percent of adults, 2 percent of teenagers and 4  percent of school-age children said they used the information to help make their purchases.