Think "ashram" and visions of a hermitage in, say, India, appear before your eyes. Perhaps you are already imagining the guru there - gentle and quiet - guiding you to an inner peace. You are surrounded by mountains. You feel tranquil. You feel spiritual. Om.

Now, type the phrase "The Ashram" into Google, and the first thing that pops up is the link to a website featuring an illustration of a chubby angel with a halo, sitting cross-legged, inviting you to come get healthy - and skinny - in Malibu.

Goodbye, India. Farewell, gentle guru. Welcome to California.

Established in 1974 by two eccentric Swedish women, The Ashram is boot camp, West Coast-style: basic training with meditation, sprouted chickpeas and a hefty price tag. It's also - and despite minimal marketing - probably the most celebrated retreat in the United States, booked solid nine months in advance.

Every week, 13 guests go through the program, sharing rooms and bathrooms in a humble house, 40 minutes from Los Angeles. Days begin at 5:30 A.M. with yoga, move on to breakfast of, say, goji berries and hemp milk, and continue with rigorous hikes, endless gym classes, more healthy food and yoga. There are no phones allowed. No Internet. No TV. And all this for $4,500 a week. Have I mentioned it's booked solid?

A lot of what makes The Ashram famous are the famous people who have gone there. Renee Zellweger signed up to lose the weight she gained for the "Bridget Jones" films. Oprah Winfrey showed up. Gwyneth Paltrow, too. Catherine Zeta-Jones and Cindy Crawford are regulars.

Another source of The Ashram's mojo is its devoted returnees. Close to 60 percent of those who do the program once, come back. In fact, there is a special deal: If you do it 50 times, you get one free. A gantze metziya, as my mother might say.

One recent Sunday - thanks to a birthday initiative from Josh, aka my boyfriend - I find myself climbing into The Ashram's white van on L.A.'s Sunset Boulevard and heading out to join the cult.

Our driver, a hot blond dude from New Mexico named Yarrow, welcomes us cheerfully: "It's going to be a superb week," he sing-songs out loud. "We have a superb group! Right on!"

I look around, futilely, for Queen Latifa. Hmm. Is anyone here famous? There is, hunched in the back, one rock star-looking guy, complete with tattoos, piercings, long jet black hair, a guitar and a blonde girlfriend in leather by his side. Hmm.

"Famous?" I lip-synch to Josh hopefully.

"I have no idea" he lip-synchs back.

Everyone else, alas, looks rather normal: A mother and daughter from Virginia Beach. Best friends from Chicago. A wealthy businessman from London. Another wealthy businessman from San Francisco. A Merrill Lynch financial adviser from Missouri. Nikki, a sporty blonde from Vancouver, and Maki and Kimimori, Japanese business partners, who arrive on a 12-hour flight in from Tokyo in their hiking pants.

The first thing we do, after a welcome snack of raw kohlrabi, is get weighed and measured around every which angle: Neck. Back. Shoulders. Hip. Thigh. Knee. Ankle. You get the idea.

And then, we pull on our expensive new hiking gear, fill up our cool CamelBaks with water, tie on our bandanas - and are off, hiking uphill at a nice, easy pace.

This is not hard at all, I think. "I'm pretty sporty," I explain in passing to Kimimori, whom we in the group have re-christened Ken and, who, it turns out, does not actually speak much English, but listens attentively as I recall my hard-core military days, 20 years ago, training kids on Gadna week in Sde Boker.

Two hours later, I am panting. We are onto the sixth mile and the never-ending uphill is not so easy after all, it turns out. "Hydrate, hydrate!" the instructors remind us over the walkie-talkies we carry, as we spread further apart.

Jaster, the rock-star-lookalike, and his maybe-model girlfriend are about a mile ahead of me, as are Nikki and Joe, the financial adviser. How frustrating! How annoying! Take a deep breath, I tell myself. This is about my journey, my challenges. But my mind keeps wandering. Don't rock stars and models smoke, drink and do drugs? How is it possible that these kids are so far ahead?

Josh, a schmoozer, is behind, happily chatting to an instructor with a perfect butt about her passion for surfing. Ayayay. "My husband just died," I hear Great-Butt saying. Double ayayay. I do not feel the Zen. I do not feel the inner peace. And by the way, I could use an energy bar.

And then, as if God has heard my prayers, I reach Bosho, the gorgeous half-Japanese instructor brought up by a Jewish lesbian couple who plays in a rock band (where do they get these people, you just have to wonder ). He is standing on a hilltop with a snack for each of us: four almonds and a prune. Four almonds and a prune? What happened to carbohydrates? I am tired. I am cranky.

Then I look around. It's beautiful. I nibble on my almonds as if they were the last morsels of food on earth, put on my iPod, and get into a groove. The sun peeps out. I pass Ken. Ha-ha. I pick a little white wild flower and put it in my hair. Life is beautiful. "Right on!" I yell out to Yarrow.

Organic tofu and quinoa

When we get back to the house, caked with mud, we sit down to lunch: raw sunflower seed salad one day; organic tofu and quinoa another. It's pretty delicious, actually. I eat the small portions with chopsticks to make them last longer. There are no seconds. No dessert. No sugar. No honey. "Hydrate," they remind us. "Hydrate."

The afternoon activities come fast and furious: aerobics and volleyball in the 98-degree-Fahrenheit pool outside, Pilates and weight training in the gym, and yoga in the yurt. We all get wiatsu sessions - an activity aptly named for shiatsu in water - which basically involves being dragged around the hot pool, with eyes closed, by an instructor, as she croons, "relax," and folds our bodies into all sorts of weird shapes. And we get heavenly massages, where we try to sneak in naps.

After dinner - coconut chipotle soup, for example, or maybe edamame with raw spinach pesto - we slink off to secretly use our cell phones, and, a little bit thinner and totally zonked, collapse into bed by 8:30 P.M.

And so it goes, with one day much like the next, except the hikes get longer and harder, up steep hills, across rocky ravines and down to sandy beaches. By the end of the week we have done more than 60 miles - and, yes, almost to my surprise, have really begun to feel and look different. All this focus on our bodies, our eating and on nature, is, it turns out, leading to some tranquility after all.

On the last day, we go in to get re-weighed and measured. Everyone has changed. The mom from Virginia Beach looks as if she has had a face-lift. And Joe has shed 16 pounds! He is almost, strangely, unrecognizable. "My friends were amazed," he admits a few weeks later, adding that he is now training for a half-marathon. "The effects are still there," Maki writes of her transformation. "Tighter stomach, great complexion, getting up well in the morning feeling ready to go."

And me? I lost a respectable four pounds. I feel great. I vow to eat small portions and healthy food for the rest of my life.

A month later, back in Paris and living directly, as one inevitably does, across from a patisserie, I have gained back three and a half pounds. Oh well. I was never one for self-discipline. But it was fun. It was a challenge. I saw some beautiful mountains. I felt I was at one with the movie-star set. I was happy. I even managed some fleeting moments of inner calm, out there in California.