Dining out is weighing on our budgets.

The No. 1 thing Americans bust their budget on is dining out, according to research released by financial company Principal. Nearly one in three Americans (29%, up from 26% last year) said that this was this year’s top budget buster for them, followed closely by food/groceries (27%). And research released Monday by financial company Fidelity found that the No. 1 small financial mistake Americans admit to is dining out too much, with 36% saying they’d done that in the past year.

Government data shows that Americans spent nearly $3,500 a year on dining out in 2018 — a 2.8% increase just from the year prior. And restaurant sales are projected to hit a record high this year of $863 billion, according to the National Restaurant Association. What’s more, as MarketWatch reported in July of this year, “the cost of going out to eat or getting takeout food is rising a lot faster than the cost of buying groceries.”

What’s more, we eat out often: Gallup data shows that six in 10 Americans ate dinner out at least once in the past week, and 16% ate dinner out three or more times. “Dining rooms and kitchens across the U.S. are getting a little less use than they used to,” research firm Nielsen noted. “That’s because Americans have embraced the experience of eating out.”

One reason dining out is such a budget buster: People who eat out a lot tend to underestimate what this will cost them, according to a 2017 study from researchers at Penn State. The researchers asked the participants what they thought they would spend eating out at the beginning of a two-week period and then in the middle of that period; participants upped their average budget from a little under $18 in week one to about $55 in week two.

"What this tells us is that obviously they thought they would spend less in a week, but as the week progressed they realized they were spending a lot more and they rationalized that increase,” says Amit Sharma, associate professor of hospitality management and director of the Food Decisions Research Laboratory, Penn State.

Not only is eating out wreaking havoc on your savings, it may be expanding your waistline. On days when Americans eat out, they scarf an average of 200 more calories than when they eat at home, according to a 2015 study of more than 12,500 people published by Public Health Nutrition. Furthermore, government research reveals that “when eating out, people either eat more or eat higher calorie foods — or both — and that this tendency appears to be increasing” and additional studies have found that dining out is associated with obesity and more body fat.

All told, nearly three in four Americans are now either overweight or obese, according to the CDC. And that’s costly: “The medical cost for people who have obesity was $1,429 higher than those of normal weight,” the CDC notes.

Still, it’s important to point out that there are plenty of other reasons Americans are overweight and don’t have fat savings accounts besides dining out often, and that people can certainly put on the pounds — and spend big — when cooking their own foods.

This story was updated on Dec. 9, 2019.