It’s easy to blame fast food for making Americans fat, since the extreme calorie counts are posted as proof right on the menu. But restaurants too small to be required to report calories and nutrition information often get a pass. There’s no way your favorite Italian restaurant can be worse for you than a drive-thru—right?

Wrong, suggests a new study published in the Journal of the American Academy of Nutrition and Dietetics, which joins other recent research finding that restaurant food is as unhealthy as the fast kind. “The places that don’t report calories are just as bad—you really don’t know what you’re eating,” says the paper’s senior author Susan Roberts, director of the Energy Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. Indeed, 92% of meals from large-chain and local restaurants have more calories than is recommended for the average person, the authors conclude.

In an unappetizing experiment, the researchers ordered takeout from 123 restaurants in Boston, San Francisco and Little Rock, Ark.—which they then took to a lab, froze in bags and shipped to Boston. There, researchers blended up the meals, freeze-dried them, pulverized them into a powder and analyzed their calorie contents.

MORE: 34% Of Kids Eat Fast Food On A Given Day

“We found what we were expecting, which is that portion sizes are obscene,” says Roberts. Some meals exceeded the calories recommended for a whole day. On average, these restaurant meals contained 1,205 calories—about half of a person’s typical daily recommendations. In all, 92% of the meals gave a typical eater more energy than they need at a single meal (570 calories, which the researchers used as a benchmark for typical energy requirements.) And there was little difference between the calorie counts of food at chain and non-chain restaurants.

The researchers sampled diverse fare, including American, Thai, Chinese, Italian, Mexican, Greek, Indian, Japanese and Vietnamese. But the most caloric were American, Chinese and Italian meals, which averaged 1,495 calories each.

MORE: 7 Restaurant Meals That Are Way Saltier Than You Think

Just knowing that a big platter of beef tacos has a lot of calories won’t help if it’s steaming right in front of you, the authors contend. “People blame themselves and say they don’t have enough willpower,” Roberts says. “It has nothing to do with willpower and everything to do with biology.” When the tacos arrive at the table, you have an “overwhelming neurological response,” she says: blood glucose drops as a signal for hunger and stomach muscles relax to make room for the feast. “Our biology is designed to make us eat when there’s food there,” she says. “I don’t think anybody should feel bad that they get weak when there’s an excessive portion in front of them, because the problem is the excessive portion, not them.”

That’s why requiring all restaurants to post calorie counts won’t solve the problem, the authors say. Their solution: require restaurants to let people order food in half portions or one-third portions, and price it proportionally. “I would eat out 10 times as much if I could order a half or a third of whatever I want, instead of being left with the miserable healthy options, which are low in calories but not as interesting either,” Roberts says.

Other approaches have tried to nudge people towards the healthier options on a menu, with mixed success. The authors know their proposed policy—which is hard to find at restaurants today—wouldn’t be easy on everyone. “Restaurants would hate it, but they would adapt by charging more for their portions or reducing portion size,” Roberts says. “Customers would love it, and it would take away the current incentive to make everything obscenely large.” By letting people choose how much they’re served, the authors say, they can eat less when they eat out without even trying.

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Write to Mandy Oaklander at mandy.oaklander@time.com.