Creator of the 'Paleo Diet' Rolls Out New Cookbook

Paleo diet founder Loren Cordain Ph.D. has released a new cookbook that gives the diet followers more ideas on how to prepare their meals.

The paleo diet consists of meat from grass-fed animals, fish, fruit, vegetables, eggs, nuts, seeds and olive oil, along with plant-based oils such as walnut, flaxseed, avocado and coconut. The diet forbids grains, cereals, legumes (such as beans and peanuts), potatoes, salt, dairy products, processed foods and refined sugars.

"We are Stone Agers living in the Space Age," writes Loren Cordain in his book The Paleo Diet: Lose Weight and Get Healthy by Eating the Foods You Were Designed to Eat.

"Nature determined what our bodies needed thousands of years before civilization developed, before people started farming and raising domesticated livestock," writes Cordain, a professor emeritus at Colorado State University.

The idea behind Paleo is to eat foods that our ancestors ate tens of thousands of years ago. Cordain claims you'll stay in shape and protect yourself better from heart disease and diabetes. He even says following the diet can even help reduce or eliminate acne.

Megan Fox and Jessica Biel are followers of the diet and vow by it.

"Our genes haven't changed a lot in the last 40 or 50 thousand years," Cordain said today on "Good Morning America." "So we do quite well on the foods that we're genetically adapted to."

However, not everyone is convinced that the Paleo Diet is healthy.

"The downfall is missing out on certain foods that many nutrition experts, including myself, feel are important to have in one's diet, such as legumes that are rich in fiber and other good nutrients," nutritionist Rachel Beller, author of "Eat To Lose, Eat To Win," said on "GMA."