© Chris Pizzello/Invision/APJack Osbourne arrives at the Critics' Choice Television Awards at the Beverly Hilton Hotel on Monday, June 10, 2013.
The theory behind the Paleolithic Diet, short-named the Paleo Diet, is that mimicking the diet of our ancestors some 10,000 years ago - prior to the European construction of the agriculture and grain-based diet - is the healthiest way to live.

Also referred to as the caveman diet, Stone Age diet and hunter-gatherer diet, the Paleo Diet is focused on avoiding refined foods, trans fat, dairy and sugar, and consuming lean proteins; fresh vegetables and fruits; and healthy fats through nuts, seeds, avocados, fish oil and grass-fed meat. Among the touted health benefits are improved blood lipids, weight loss, and reduced pain from autoimmunity. And the diet is scientifically proven to help stave off degenerative diseases such as obesity, cancer, diabetes, heart disease, Parkinson's, Alzheimer's, depression and infertility.

In a 2007 study comparing the Mediterranean and Paleo diets, the Paleo Diet group reversed the signs and symptoms of insulin resistant, Type 2 diabetes. Meanwhile the group practicing a Mediterranean Diet experienced little to no improvements.

While a number of gastroenteroligists and other doctors have reintroduced the Paleo Diet over the past several decades,Robb Wolf, author ofThe New York Times best-selling bookThe Paleo Solution: The Original Human Diet, has the been one of the strongest forces in popularizing the ancient diet that humans subsisted on for some 2.5 million years.

Now celebrities are professing the benefits of the Paleo Diet.

1. Jack Osbourne

At the mere age of 26 and a new father, Jack Osbourne was diagnosed with multiple sclerosis in spring 2012, reported ABC News.

The autoimmune disease affects the brain and spinal cord. Approximately 400,000 Americans suffer from MS, according to the National MS Society.

But Osbourne is taking a proactive approach to fighting the symptoms of MS. His motto? "Adapt and Overcome."

"Diet is a big thing. I am a firm believer in you are what you eat. I juice a lot, I try and stick to a Paleo Diet. At its core, I look at MS as inflammation, so I try and eliminate foods that cause inflammation: dairy, gluten, grains."

Osbourne stays inspired by the story of Dr. Terry Wahls, who defeated the progressive disease without drugs by treating food as medicine.

2. Megan Fox

Transformers star Megan Fox is rumored to practice a Paleo lifestyle, with a penchant for enjoying almonds for dessert. Perhaps Fox is simply paying tribute to her roots. Fox has said that she'd really like to play the Apache superhero Rainmaker if the Gen 13 comic book were ever made into a movie. In slightly defensive remarks, she said she wouldn't want "people" (presumably Indians) to "protest" if she were in the role: "She's a Native American and I have a little bit of that blood in me. ... It would be a bit of a stretch - but if Jake Gyllenhaal can be the Prince of Persia, I think that I can do that."

3. Jessica Biel

Actress Jessica Biel has said, "I do a lot of cooking at home using fresh fish or lean meat like chicken and vegetables. I eat well. I don't like the word 'diet'."

The CrossFit enthusiast beams that the Paleo diet "just leans you down and slims you up and takes that little layer of fat, skin, water-weight right off your body."

4. Miley Cyrus

After the media began hurling accusations at Miley Cyrus that she has an eating disorder, she confessed her diet change. The singer and actress has gone Paleo, she said, primarily emphasizing the gluten-free attributes of the lifestyle.

"Everyone should try no gluten for a week! The change in your skin, physical and mental health is amazing. You won't go back!" Cyrus said. "It's not about weight - it's about health. Gluten is crap anyway!"

5. Matthew McConaughey

McConaughey is pretty strict about eliminating all processed grains and refined sugars, plus he engages in intermittent fasting. "...I have a job where I like to look good and be as healthy as possible," he has said.

But the man named 2005's Sexiest Man Alive by People Magazine says he cuts himself some slack 10 percent of the time so he can chow down with his kids.

6. Eva La Rue

On Robb Wolf's Paleo Solutions website, CSI: Miami star Eva La Rue says, "I am a firm believer in The Paleo Solution. I maintain a hectic schedule that starts early and finishes late. Filming a television series, maintaining my fitness, and being a mom can be harrowing some days. Since adopting a Paleo way of eating I look and feel better, and I know that I am setting a good example for my daughter."

7. Ursula Grobler

"When I'm close to a competition, I'm super-strict Paleo," said Ursula Grobler, the current world record holder in the indoor ergometer, and one of the world's best lightweight rowers. "It helps me get the leanness I need to compete, while still supporting good eating habits."

8. Becca Borawski

"On Paleo, my body fat is lower, energy levels seem higher and my performance is better," said Becca Borawski, program director at CrossFit LA. "But because it's so restrictive, I do it five or six days of the week."

9. Aaron Rodgers

Green Bay Packers Quarterback Aaron Rodgers brought his copy of The Paleo Diet on his road trip to Super Bowl XLV in Dallas. Naturally, they won.

According to John Durant, author of The Paleo Manifesto: Ancient Wisdom for Lifelong Health, Rodgers contemplated packing his guitar, but then didn't think he'd have time to play. The Paleo Diet made the cut.

10. Andrew Flintoff

Professional boxer and retired England cricket captain Andrew Flintoff gave up alcohol and adopted the Paleo Diet last year.

"I've lost about 30lbs in the last seven weeks and I'm trying to lose another 15," he told the Daily Mail in October 2012. "I'm on the Caveman Diet."

Asked by the Daily Mail what he can eat, Flintoff replied: "I have steak or two buffalo burgers for breakfast. It sounds good, but when you're up at half five in the morning cooking up a steak, it's dreadful.

"Then I have 12 almonds mid-morning, two chicken dinners a day with green vegetables, two boiled eggs or some berries mid afternoon and then fish and green vegetables for dinner."