WE WERE ON our way to lunch when I decided to share some diet wisdom, compliments of "The Real Housewives of New York" star, Bethenny Frankel.

"No one ever got fat on a cookie," the svelte reality-TV star had declared by phone.

That caught my lunch buddies' attention as I'd known it would. The subject of weight control always is a great unifier when girlfriends gather. Women of all body types and sizes tend to bond around the subject of weight, dispensing tips - some more useful than others. That's how, over the years, I learned about the cabbage-soup diet, the cookie diet and the eat-nothing-white plan.

By now, though, most women in my circle have sworn off dieting, hopefully for good. We've finally gotten the message: Diets don't work. Oprah Winfrey's public struggles with weight over the years is Exhibit A. Actress Kirstie Alley, who used to shill for Jenny Craig before her weight ballooned back up, is another.

"Most people who have weight issues have food noise. They are obsessing. They're afraid to be thin," Frankel told me. "Some people won't allow themselves to be happy. They constantly torture themselves."

Luckily for me, weight's not my biggest issue. I mostly have stayed within a 10-pound range of the same weight for most of my adult life. But since I was fresh off one of those weeklong Caribbean cruises where the primary entertainment is bellying up to the buffet, I appreciated hearing Frankel's common-sense advice even if there was nothing new about it: Taste everything, eat nothing. And you can have it all, just not at once.

"You don't punish yourself. That's what having a good relationship with food is about," Frankel said in that rapid-fire fashion of hers. "You can have a cookie. You can have fried chicken. You can have it all. You just can't go to that place where you are punishing yourself."

Common sense, right?

Yeah, but if that's all it took, "The Biggest Loser" would have gone off the air long ago.

People love this stuff.

Earlier this spring, when People magazine placed former teen star Valerie Bertinelli on its cover after she dropped 50 pounds, it became the year's second-biggest seller. Last week, a bikini-wearing Melissa Joan Hart graced the cover, trumpeting her post-baby slim-down.

An age-old axiom in publishing is that "sex sells." Well, weight loss does, too. Frankel's book, "Naturally Thin: Unleash Your Skinnygirl and Free Yourself from a Lifetime of Dieting," has been selling like hot-buttered pancakes - not that Frankel would allow herself to eat a double stack.

And if the divorced natural-foods chef does slip up, you won't catch her banging herself in the head with one of her designer stilettos.

The way she sees it, your diet is a bank account. Just as you balance your financial affairs, you should do the same thing with your food intake.

"People say, 'I was good' or 'I was bad,' " Frankel said.

"It makes me cringe now whenever I hear people say, 'I was so bad.' "

"This weekend, I was in Vegas and I had a giant meatball dinner," continued Frankel. "I'm not thrilled that I drank and I had 42 meatballs. You don't punish yourself. That's what having a good relationship with food is about." *

Bethenny Frankel, one of "The Real Housewives of New York City" and author of "Naturally Thin: Unleash Your Skinnygirl and Free Yourself from a Lifetime of Dieting," will sign copies of her book from 1-3 p.m. Friday at Skirt boutique, 907 W. Lancaster Ave., Bryn Mawr.