Want to impress your friends with a near-impossible feat? Spend five days in New Orleans on a diet.

“You could eat 24 hours a day in this town, all different things, and still not eat all the things you planned to eat on your first day here,” said Julie Jules, a jazz singer who appears in the nightly live music “Salute” to Louis Armstrong at Satchmo’s Place (320 Decatur, 504-569-1401; $29 entrance including free drink).

Despite being rail thin, Ms. Jules speaks the truth. On previous visits to New Orleans, I’ve spent the cab ride from the airport mentally lining up a long litany of famous dishes I’ll soon be eating: crawfish etouffee, gumbo, jambalaya, and fried oyster po’ boys, topped off with a dessert of pralines and bread pudding with whisky sauce, say. And here I was now, hoping to drop a few pounds.

In theory, there were reasons to be cheerful. During the strictest phase of the Atkins diet, my torture of choice, you are allowed to eat generous quantities of protein and fat. That means steak with bearnaise sauce is on the menu, as is cheese, mayonnaise, seafood, and a wide range of vegetables. However, sugar and starchy carbohydrates such as potatoes and flour, are out of the question. And as it turned out, almost every blessed dish in the city had a flour-thickened sauce.

“Pretty much everything here starts with a roux,” said the waitress at K-Paul’s Louisiana Kitchen (416, Chartres St., 504-524-7394), one of the more well-to-do restaurants in the Big Easy. Certainly, the restaurant’s provenance doesn’t inspire confidence in anyone seeking slimming fare – it was established by Paul Prudhomme, “the fat guy you see on TV,” as the concierge at the Hyatt put it. But Fat Paul’s joint was by no means unique. I encountered the roux problem at restaurant after restaurant. I also encountered genuine regret on the part of wait staff forced to deny me the most delicious stuff on the menu. That look of surprise, then concentration, followed by an open-palmed gesture of apology – could it be called “rouxful”?

Sometimes there were options. At KPaul’s, they fitted out my stuffed pork chops ($27.95) with a flourless brown butter and garlic sauce instead of the Marchand du Vin sauce it normally comes with. But the Marigny Brasserie (640 Frenchman St., 504-945-4472), in New Orleans’ newly trendy Faubourg-Marigny neighborhood, just east of the French Quarter, was less scrupulous. My T-bone lamb chops ($27) were denuded of blue cheese grits, but the plate came adorned with a rich circle of sauce that had the tell-tale glossiness of flour. Further more, the caramelized onions that accompanied my excellent carpaccio ($10) had a suspicious sugar kick.

Nevertheless, there were outstanding feats in the line of duty. Derrick, the waiter in the beautiful courtyard restaurant at the Court of Two Sisters (613 Royal St., 504-522-7273), checked with the chef on two separate occasions about lurking carbs. Sadly, this rendered the otherwise fabulous jazz brunch buffet ($25 a person) a very limited affair for me – boiled shrimp and crawfish, iceberg lettuce, tomatoes in vinaigrette, and a boring ham and cheddar omelet.

Never mind, my husband cheerfully compensated for all this by sampling nearly all the 75 items on the steam tables. He was particularly selfless in sampling desserts on my behalf, declaring the pecan pie and bread pudding at Two Sisters good enough to break my resolve (I held fast). At the Marigny Brasserie that evening, the waitress’s recitation of available desserts went on for a good two minutes. At that point, I simply laid my cheek on the tablecloth and sobbed, while my husband cheerfully ordered a trio of creme brulees over my head.

Dessert was, I confess, a major temptation, but not the hardest one. You can’t drink alcohol on Phase One of Atkins, and if the residents of New Orleans are all about food, the city’s visitors are all about drink. Bourbon Street, the main drag of the old French Quarter, may have been named after a French count, but the reference to strong liquor couldn’t be more appropriate. It’s teeming with drunken frat boys on spring break and roving gaggles of bachelor and bachelorette parties, all clutching their drinks in garish plastic containers.

I’ve been on Bourbon Street before and found it a little intense but mostly funny. However, that was when I, too, had a squashy cup of Hurricane cocktail in my hand, and several already in my belly. Let’s just say that come Friday night I was the only sober person in New Orleans. It’s not easy, you know, being designated driver for a whole city. True, I could compensate with prime rib, but I felt like a prime rube.

On day four, we met friends for lunch at Flaming Torch (735 Octavia, 504-914-1856) in the city’s Garden District, just off Magazine Street. Unfortunately, our waitress seemed unable to conjugate my stated needs through my order. So I ended up with a beautiful fillet of cod swaddled with out-of-bounds wild rice and carrots. “You can’t eat carrots?” my husband asked incredulously, as he ordered his second Bloody Mary (he declared it the best in town). “This city seems completely obsessed with food,” I said exasperatedly to my friend. She nodded slowly. “It will confound you,” she said, in the way that only someone with a beautiful Southern accent can get away with. “Yes, but at least you die happy,” her husband said across the table, and smiled broadly over a lunchtime bourbon.

Virtue intact, I abandoned my husband to explore the five-mile strip of wildly eclectic shopping Magazine Street has to offer. But after all that virtue, I was too depressed to shop.

And so, finally, on the evening of Day Five, primping testily in front of the hotel room mirror, I cracked. “Oh, for goodness sake, let’s go out properly for our last night here,” I said. And it was glorious to sit down to real drinks at the Gennifer Flowers’ Kelsto Club bar (720 St. Louis St., 504-524-1111), with live piano and trumpet. Posters claimed that Ms. Flowers’s appeared “nightly,” but apparently Sunday wasn’t her night, so, instead, we watched the evening gather momentum through the open windows of this high-ceilinged, 19th-century drawing room, the roar of nearby Bourbon Street rendered almost romantic with the help of vodka Gibson cocktails.

Later in the evening, we stumbled across a joint called Fiorella’s that turned out to serve the best fried chicken I have ever had (45 French Market Place, 1136 Decatur St., 504-528-9566; fried chicken platters starting at $8.25). I washed it down with a stimulating Cajun martini, and oh, it felt good to roam free around the food groups again. Later, listening to excellent jazz played by Ryan Burrage and His Rhythmaker at Fritzel’s (733 Bourbon St., 504-561-0432), I even lit a borrowed cigarette and inhaled the full magic of the city for all the senses.

Leaving on a 6:30 a.m. flight Monday morning, my husband and I stumbled, bleary-eyed and hung over, through security with all the other bleary-eyed, hung over travelers, and I reflected on the pros and cons of abstinence. The writer Martin Amis once argued that it boils down to this question: Do you want to feel good now or good later? Or, in the case of dieting: Do you want to feel good now or in a month or so? New Orleans offers a powerful argument for seizing the beignet and the moment while they’re there, if only once in a while. And, hey, when I got home, I hadn’t gained an ounce. How many visitors to the Big Easy can say the same?