"I can spot an acid body across a room," says Lindsey Duncan, a naturopathic doctor who has helped remold the bodies of Marc Jacobs, Demi Moore, and Miami Dolphin Reggie Bush. "The hair and the skin are dried out, the skin pores are too large, and everything is starting to age prematurely."

Natural-cure advocates have long promoted a diet aimed at increasing alkaline in the body—heavy on fruits and vegetables, light on meat, dairy, sugar, and grains—but this way of eating showed up on the radar only after a recent explosion of interest among A-list celebrities.

Mainstream medical experts call foul, arguing that the body tightly regulates blood pH, regardless of the food we eat. (Chemistry refresher: The pH scale runs from 0 to 14—water has a neutral value of 7, higher being alkaline and lower being acid.) But new research suggests that what the body does to regulate pH can lead to thinner bones and weaker muscles. (Duncan credits Reggie Bush's alkaline diet with helping him rebound from a broken leg.) According to Kimberly Snyder, another nutritionist for the celeb set, the diet also delivers a leaner body—you're shedding pounds by switching out processed carbs for fruits and vegetables. And there are other, less tangible benefits. Snyder's client and this issue's cover subject Channing Tatum says that a daily high-alkaline smoothie "makes me feel good."

But how do we know it's the alkaline that's doing the heavy lifting, as opposed to the fiber or the phytonutrients? Sheila Dean, a nutritionist at the University of Tampa, says, "The important thing is to eat a mostly plant-based diet to get those alkalinizing minerals like magnesium, potassium, and calcium. The body doesn't care what you call it."

Nutritionist Kimberly Snyder explains how three of her A-list clients benefit from the
alkaline diet.

Josh Duhamel
"Drinks the Glowing Green Smoothie every day, which is made of the most alkaline foods—greens and fruit. He says it gives him a ton of energy for workouts."
Mark Ruffalo
"He switched to a largely plant-based alkaline diet after working with me during The Avengers. He lost weight and told me, 'I feel so great I never want to go back.'"
Chris Hemsworth
"We exponentially increased the greens in Chris' diet, which helped alkalize the body and balance the acidic foods, namely animal protein."

Also on Details.com:
The Ultimate Guide to Vitamins
Detox Nation: The Cult of the Cleanse
Do You Know the Ingredients in the Virility Diet?