‘Aghhhhhhh!”

That is the sound (pretty much) of millions of hitherto happy-go-lucky New Yorkers fleeing Starbucks, Dunkin’ Donuts, and all the other chain restaurants they used to love. They were just about to order a muffin, maybe, or were pointing to a scrumptious scone when, suddenly, a number loomed up, big and blazing as a barbecued boar:

The calorie posting, required by local law as of May 5.

Corn muffin: 510. Sticky pecan roll: 780. Little ol’ Munchkin: 80. Eighty calories for a mere mouthful of fun? It was more than many New Yorkers could bear. Off they ran to the fruit stand, just as the Health Department hoped.

Or off they went to eat their treat anyway. But at least now they feel really horrible about themselves.

“Since they started posting the calories, I stopped eating pretty much everything they have at the counter,” an attorney drinking coffee at a downtown Starbucks, Joe Molloy, said.

Writer Jodi Lipper is a numbed nosher, too. “I stand on line at the Starbucks every day, right in front of the pastry case, but oh my god,” she said. The calorie counts took her completely by surprise and she’s the author of a diet book, “How To Eat Like A Hot Chick.” “There’s a low-fat chocolate banana chip loaf that’s 400 calories for a tiny slice,” Ms. Lipper said. “A muffin that’s not going to fill you up is 500.” Add that to a venti mocha or frappuccino, “and you’ve got a 1,000 calorie breakfast!”

Or, more to the point, you don’t. Like Mr. Molloy, Ms. Lipper has severely curtailed her Starbucks habit, as have a whole lot of locals. Ever since the calorie signs went up, one barrista confided, pastry sales are down between 15% and 20%. And let’s not even talk about what’s going on at Dunkin’ Donuts.

Or let’s, but in a sec. First let’s talk about whether there is any merit to this new law, which is being fought by the restaurant industry in appeals court even as we eat. Er … speak. Is it a great public health initiative or yet another helping of nanny-knows-best?

“I’m telling you, New York is on a rampage to make its residents healthier,” the director of physical activity and nutrition at the New York City Department of Health, Cathy Nonas, said.

I’ll say. Our city was the first in the nation to ban trans-fats — an initiative later adopted by cities from Philadelphia to Seattle — and our smoking in ban in bars was a groundbreaker, too.

Surprising as these laws were (and protested by the food-and-drink industry all the way) they were, eventually, welcomed by most New Yorkers. Why should we have trans-fat hidden in our fries? Why should smokers get to stink things up for the rest of us?

But the calorie postings are different. As a spokesman for Dunkin’ Donuts, Stephen Caldeira, said, “Dunkin’ Donuts has been providing nutritional information to our customers for several years through in-store brochures and our brands’ websites.” So have most of the other chains (and the law only applies to chains with 15 or more outlets). If the information is already available to anyone who wants it, why plaster it on the menu board?

Because without it, we are all turning into Fudgy the Whales.

Look, even that diet book author was thrown for a loop by the calorie counts right in front of her nose. So was the lady from the health department — Ms. Nonas. “It’s hard even for a dietician to calculate calories when you’re looking at the food,” she said. In fact, she was shocked to learn the true calorie count in several of the appetizers at Chili’s and Applebee’s.

Maria Vizzi, a speechwriter, was shocked, too. She went to T.G.I. Friday’s with some friends two weeks ago, “And we had the hardest time figuring out what to eat because we got hung up on the calorie counts. A few of us picked the lowest calorie item — shrimp with broccoli — and it was pretty awful,” she said. Normally the gang would have drowned their disappointment with a bunch of desserts, “But the counts set us back again and we all six shared a slice of peanut butter cake.”

Woo hoo! So much for nightlife capital of the U.S.A.!

Now, it’s not surprising to most of us that T.G.I. Friday’s food is fortified with fat. But it’s not surprising that seeing this fact in black and white puts a damper on festivities, either. Sort of like seeing a poster about herpes at an orgy. Still, the poster has a point: Watch out! Which is what some folks are now doing, food-wise.

“I used to buy Dunkin’ Donuts all the time,” an iron worker from the Bronx, Randy Zayas, said. “I stopped going because of the calories.” Mr. Zayas was coming out of a Jamba Juice where he now buys a 180-calorie fruit-and-soymilk shake for breakfast each day. In the month since he made this switch, he says, he’s lost eight pounds.

It’s not that every New Yorker needs to give up donuts. It’s not even that New York needs wispier iron workers. But we do need this law, because without it, would restaurants ever tell us, straight to our face, the waistline wollop they’re packing?

Fat chance.

lskenazy@yahoo.com