Dining by numbers

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Stephen Klein would hit the roof if he found out how many calories are in some of his favorite NYC meals.

When it comes to dishes like the bacon at Peter Luger, “so amazingly thick you can cut it like it’s a steak,” the 31-year-old hedge-fund founder prefers a policy of don’t ask, don’t tell.

And the home fries at the original Palm restaurant?

“It would blow,” he says. “It would take away the romance, or at least the gluttony, of dining out.”

Plus, adds Klein, “I’m [always] trying to convince my girlfriend to eat something. If the calories were listed? It’d be completely out the window! ‘Oh, honey, let’s share the gorgonzola popovers at BLT? Wait, they have 1,500 calories?’ No way! It’s over.”

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But Klein and other diners may not have much of a choice, as more city eateries take it upon themselves to keep their customers calorie-conscious.

It’s been just over three years since New York City made it mandatory for chain restaurants to post the calorie counts of their food and drink items.

Now, fine restaurants are jumping aboard the calorie-counting craze, too — but this time, it’s by choice, not law. Eateries ranging from trendy Koi to business-savvy Gaby’s at Sofitel are feeding into New Yorkers’ diets — and guilt — by offering special low-cal items. Rouge Tomate on the Upper East Side even introduced a surprisingly filling tasting menu in April that clocks in at 1,000 calories.

And while some city dwellers are eating up the lean-cuisine craze, others say that knowing the calories in their food and drink just amounts to one big buzzkill.

“As a customer and as a customer who also owns restaurants . . . I think mystery is really good,” says Ken Friedman, who owns such deliciously artery-clogging eateries as the Spotted Pig and the Breslin.

“We shouldn’t announce how many calories are in things or how much alcohol is in wine versus beer versus scotch.”

“I kind of don’t want to know how many calories are in a steak in Minetta Tavern,” he adds.

“That’s why people have oatmeal and yogurt for breakfast, so they can go out for dinner with little regard for the calories or fat in a dish.”

But others say there’s nothing wrong with making healthy eating easy.

On a recent Monday evening at Flex Mussels in the West Village, Magnus Riddiford and a friend, Rachel Berry, delved into their shared plates of mussels and tuna crudo with gusto. The best part of their post-work grubbing? The entire meal was only 250 calories per person.

The duo’s decision to order off of Flex Mussels’ new “Flex and Fit” menu, which launched in late June, was both a pragmatic and health-conscious one. Riddiford, the 33-year-old owner of Tablelands Wine Company, kept it light because he planned to hit the gym afterwards, while Berry, a Hell’s Kitchen resident, just wanted to leave extra room for the restaurant’s doughnuts.

“These low-calorie, lighter options are really great because you still get to indulge in dessert after and not feel so full and bad about yourself,” says the 23-year-old sales consultant.

Room for dessert is an upside, but is it worth sacrificing the special quality of dining out?

“For a nice restaurant, I do think it would be a turn-off because you’re really there for the experience and the ambience. And usually nice restaurants have reputable chefs. You don’t need to know how many calories are in something,” says NYU grad student Mandy Yeh, 25.

Nonetheless, Yeh shared a skinny chicken wrap (171 calories) and skinny crab ceviche (135 calories) at Koi, while having lunch with her friend, Lindsay Simon, 21, who was trying to eat healthy for an upcoming wedding.

“It tastes skinny to me,” says Simon of her meal, “but I’d rather know what I’m eating.”

But others say that when it comes to dining, ignorance is bliss.

“When I go out to eat, I’m not too worried about what the nutritional stats are of my food,” says Shehzad Qayum, a 24-year-old SoHo resident who eschewed Flex’s skinny offerings for the $20 all-you-can-eat mussels special, with fries.

He might be better off for his ability to ignore the low-cal fare.

Brian Wansink, a food psychologist and professor at Cornell University, says that providing calories puts a universal damper on the dining experience. Plus, it’s not really that effective at positively altering diners’ behavior.

“What we’ve found is that the people who [calorie counts] influence most are the people who care . . . with the people who are less concerned, it has no effect,” he says.

“But almost uniformly, everyone rates the meal as less enjoyable.”

Enjoyable or not, it hasn’t stopped health-crazed New Yorkers from taking tally.

At Flex, waiter Andre Taliano says that 25 to 30 percent of patrons order the “fit” dishes (which are offered verbally as a special). Jon Pinto, a waiter

at Koi, says that one in 10 guests orders off the restaurant’s skinny menu, which is printed on a placard for dinner and provided verbally for lunch. The success of Havana Central’s low-cal

drink menu, which launched in June, has no doubt been aided by the restaurant’s Wednesday skinny margaritas special. And at Morton’s steakhouse, 25 to 30 percent of guests are guzzling down drinks from its 2-month-old low-cal cocktail list, according to bartender Anthony Anthony — a surprisingly hearty percentage for a wine-heavy spot.

As widespread as the trend

has become, Cathy Nonas from the NYC Department of Health and Mental Hygiene admits that not every city eatery has the capacity to count and publicize calories. (It can be costly, as special equipment is needed and a nutritionist must be hired.)

Nonetheless, she hoped that after the city regulated chains, “it might put some pressure on [all] restaurants to make a change.”

She’s noted a growing number of restaurants adding low-cal items, and she hopes more will follow suit.

“We’d like to see more. We’d obviously like this to be a part of every menu,” she says — adding that, ideally, restaurants would “change the menu so that lower calorie items are up on top.”

Nonsense, says Wansink, who thinks that New York dining establishments might end up regretting their low-cal menus.

“People are paying for the experience; they’re not paying for the calories. And all of a sudden [the restaurants] say, ‘Look, your birthday is going to be a whole lot less enjoyable because of all the calories on the menu.’ Where do you think they’re going to want to go for their birthday next year?”

dschuster@nypost.com