I visited the headquarters of Gwyneth Paltrow's company, and it wasn't how I thought it would be

Donna Karan and Demi Moore are just two among many celebrities who have raved about the diet regime that just about everyone associates with Gwyneth Paltrow.

Indeed, if celebrity endorsements were proof of a product's effectiveness, the Clean Cleanse that Gwyneth is always talking about would be beyond criticism.

So it seems to me that the obvious place to start my investigation of the cleanse is in London, home of Gwyneth's booming e-commerce company, Goop.

I figure I will ask the employees of Goop about the Gwyneth-inspired cleanse experience before I try it myself. Gwyneth often writes about it in her Goop blogs.

She has said, "This thing is amazing," that it "worked wonders," and that it made her feel "pure and happy and much lighter." She has also noted that it is something that she does with the whole "Goop team."

Given the warm and friendly vibe on the Goop website - it was, after all, to quote the website, "created to celebrate all life's positives" - I am expecting a warm and happy vibe at Goop HQ.

I am mistaken.

I ring the buzzer to request entry to the second-floor office. No response. I try again and then again. Still no response. I implement Plan B. As a courier is buzzed up, I do the classic foot-in-the-door move. I feel like Jason Bourne.

I confidently walk up to the Goop receptionist and give her a friendly hello. She does not say, "May I help you?" or even "Do you have an appointment?"

Instead I get a blank Goopless stare. Undaunted, I ask to see someone about the cleanse, trying my best to give the impression that I am here for a prearranged meeting. She looks at me as if I am a homeless man asking for spare change.

In other words, she doesn't look at me.

She picks up the phone - still not a word to me - to tell someone about my presence in the office. Then I wait. And wait. Just when I start to fear a Goop security guard will appear, doubtless wearing a tasteful Stella McCartney - inspired ensemble, a young woman approaches me.

"You're here to talk about the Clean Cleanse?" she says brightly.

"That's right," I say. "I'd really like to know more about what actually takes place in the cleanse. I want to get some details about the process and the science behind it."

She smiles. "What a good idea."

"Thank you," I say. "Who would you suggest I speak with?" I imagine Gwyneth herself now cooperating with my investigation.

"I would say Dhru Purohit," says the charming young lady.

I take out my notebook, expecting her to lead me down the hall to the office of said person.

"And where would I find him?"

"Santa Monica, I believe." Her smile now is accompanied by an arched eyebrow.

"Which is where the Clean Program is based. You know that, right? That they're the company that makes the Clean Cleanse?"

I close my notebook. Jason Bourne did not have to implement Plan B to exit the building.

After a few phone calls and e-mails about my desire to do the cleanse, Dhru Purohit has a kit sent to my house (the usual price is $425). He also invites me to the Santa Monica office to obtain some precleanse advice and to meet the guru himself, Dr. Alejandro Junger.

The building is inconspicuous. It is not the type of structure you would expect for the head office of a wildly successful diet company.

The Clean Program has produced several international best-selling books and tens of thousands of Clean Cleanses, which the company website heralds as "the most endorsed, supported and effective cleanse in the world."

And yet its offices, just a block off Los Angeles's often-sung-about Santa Monica Boulevard, look like a modest walk-up apartment.

"Do they live here?" I wonder as I approach the door.

There is no sign announcing the name of the company. There isn't even a nameplate. There is just a buzzer.

But if the building is understated, its occupants are not. When it comes to life's positives, the Goop team in London could learn a thing or two from Dhru Purohit.

This guy is fun. He is all energy, enthusiasm, and commitment.

"Hey, Tim!" Purohit says with a big, welcoming smile as soon as the door swings open.

He invites me into the company's modern work space, which looks more like an open-concept home than a business.

No offices, cubicles, or desks in sight-just a large kitchen and several comfy-looking sofas and chairs. Purohit tells me he is "a Sherpa of sorts." He's a guy who "enjoys guiding people and communities through the world of holistic healing and spiritual living."

And he believes in the cleanse product the way Napoleon believed in the flexible use of artillery. It may not be easy to implement, but it can change the world.

Dr. Junger is scheduled to arrive in a few minutes, so I take the time to ask Purohit about what I view as the biggest challenge associated with the cleanse: no coffee.

"I am a coffee addict," I tell him. "I love coffee. I cannot stress this enough. It is central to my very existence. Are you sure I must give it up?"

"You must give your adrenals a rest," he explains. "And you must remove the dependency. The idea that you need coffee to function, long term, stresses your adrenals. Your adrenals are your energy bank account."

I will hear the word adrenal - which, I assume, is a reference to the hormones secreted by the adrenal glands - approximately nine thousand times during my interactions with the Clean Program teams.

Adrenal glands. Adrenal fatigue. Adrenal stress. Adrenal rest.

Moments later Junger arrives. I will say this about the man: he projects a relaxed energy. He's got his adrenals in check, obviously.

Junger is a physician from Uruguay.

He is the inventor of the Clean Cleanse and is often described in the popular press as Gwyneth Paltrow's doctor, though "spiritual leader" would probably be more accurate.

Indeed, Gwyneth's best-selling cookbook, It's All Good, is dedicated to, among others, Junger, whom she describes as "my good friend."

The book contains recipes inspired by Junger's diet and health philosophy. In the preface, she credits him, and the Clean Cleanse, with curing her of a variety of ailments, including an intestinal parasite that went undetected by Gwyneth's conventional physicians, the adjustment of her "sky-high" adrenals, and the unclogging of her horribly clogged liver.

Given all this Gwyneth-attention, it is no surprise that Junger is a bit of a celebrity himself, appearing on programs such as The Dr. Oz Show, where Junger provides detoxing and cleansing advice.

Excerpted from "Is Gwyneth Paltrow Wrong About Everything? How the Famous Sell Us Elixirs of Health, Beauty, and Happiness", (Beacon Press, 2015). Reprinted with permission from Beacon Press.