Critics have attacked chain restaurants for years, complaining about high-fat, high-calorie meals turning America into a nation of artery-clogged fatties. But a new study has found that local mom-and-pop restaurants aren’t much better.

In 123 restaurants in Boston, Little Rock, Ark., and San Francisco, the research team found that a single meal serving, without beverages, appetizers or desserts sometimes exceeded the caloric requirements for an entire day.

The study was conducted by Tufts University researchers who analyzed the calorie content of frequently ordered meals in both local restaurants and their large-chain equivalents in three separate locations. The data were collected between 2011 and 2014 by comparing the meals against human calorie requirements and USDA food database values. The cuisine studied by researchers included American, Chinese, Greek, Indian, Italian, Japanese, Mexican, Thai and Vietnamese fare.

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The study, which appears today in the Journal of the American Academy of Nutrition and Dietitics, also found that American, Chinese and Italian had the highest calorie counts with a mean of 1,495 calories per meal.

Susan Roberts, lead author of the study and director of the director of the Energy Metabolism Laboratory at Tufts, said she decided to do the study after she was struggling with her own weight issues and decided to test the caloric content of some of the restaurant meals she was eating.

“This started when I was 50 pounds overweight and I was eating in Chinatown,” Roberts said. “I said I’m going to take some of those containers back to the lab. We couldn’t find any listings in the USDA food database for kung pao chicken or lasagna. They are just guessing.”

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To get a handle on how many calories are in restaurant meals, the team ordered food to go, packed it in freezer bags and dry ice, and then shipped the containers to Boston. There, the team blended, froze and turned the food into a powder which could be analyzed in a laboratory using a “bomb calorimeter” to determine the calories.

Roberts says that humans are hard-wired to pig out, even when they don’t need the food to survive.

There’s a well-defined biology of over-eating that has nothing to do with willpower,” Roberts said. “When faced with a large plate, we experience a huge neurological surge which activates in real biology hunger. You get a surge of insulin, which drops your blood sugar. A few minutes after standing in the line for a coffee, then you end up buying two donuts. It’s your neurological reflexes. Those same reflexes relax your stomach muscles so you have a bigger stomach. All these mechanisms are pure biology.”

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Roberts and her colleagues believe that restaurants offer way more food than needed because they are afraid that some people will walk away complaining about not enough. The group says they are advocating for “proportional pricing” at restaurants so that people who order and eat less, pay less.

“If I as a small woman walked into a restaurant and said ‘I want a third of a portion,’” Roberts said, "they would give me a third portion and I would pay a third of the cost. Restaurants would hate this at the beginning. But they would do it.”

Christin Fernandez, a spokeswoman for the National Restaurant Association, says that diners have choices when they eat out. They are also providing people with more information about caloric content of foods.

"Obesity in America is a complex issue that must be approached at a holistic level," Fernandez said in a statement. "The industry has been making significant strides in providing consumers with an increased choice in healthful menu options. With over one million restaurants nationwide, consumer response and confidence is a top priority. Eighty five percent of American adults say there are more healthy options at restaurants than compared to just two years ago. Through our Kids LiveWell nutrition program and our work on supporting the FDA’s national menu labeling standard for chain restaurants, the National Restaurant Association is working to move the industry forward as a whole to help empower consumers to make nutritious choices when dining out.”