What do Miley Cyrus, Jessica Biel and Megan Fox all have in common? They've all jumped on the paleo diet bandwagon at some point. The paleo diet — also known as as the Paleolithic diet or caveman diet — is a high protein, low carb diet based on the foods that were once eaten during the Paleolithic period.

The main components are foods that someone of the hunter-and-gatherer time period would have consumed. Meats, vegetables, nuts and fruits are some of the staples items. Things like processed breads, sugars, certain legumes, and foods to which a caveman would not have had access aren't allowed. Some health critics have said this this diet might be too restricting and a recipe for failure. The restricting nature of the diet might cause someone to forgo his or her eating plan and inevitably binge.

The paleo diet also restricts dairy, things like milk, yogurt and cheese are necessary for calcium intake and bone health.

In an interview with the Huffington Post, Joy Dubost, a registered dietitian and a spokesperson for the Academy of Nutrition and Dietetics stated her belief that this diet might be restricting of very important nutrients.

"It has eliminated several food groups like dairy and grains, which provide essential nutrients, such as calcium, vitamin D, magnesium and phosphorus in dairy and B vitamins, fiber and antioxidants in grains," Dubost said. "Legumes also provide a great protein source with little fat and lower in calories while providing essential nutrients and fiber."

However, some research has shown that the benefits might actually prove to be successful in the long run. In a clinical study in Sweden conducted by Lund University, researchers found that people who followed the paleo diet in a three-month period had an improvement in their glycemic control, which ultimately improves their cardiovascular risk factors.

"The study supports the initiation of a large scale study on the effect of Paleolithic diet in subjects with type 2 diabetes," according to researchers.

The glycemic index is a measure of how quickly a persons blood sugar levels rises after eating certain foods. This has been the only major study of the paleo diet to date, and more research is needed to determine the significant success or failures that it might have.

Here is a general list of some of the food do's and don't of the paleo diet:

Paleo Do's:

  • Meat
  • Fish
  • Eggs
  • Vegetables
  • Fruits
  • Nuts

Paleo Don'ts

  • Legumes
  • Dairy
  • Starches

With all old or new diet fads, like the Atkins diet, Juice Cleansing, Blood Type Diet and many others, a bit of caution should be taken and a trip to your primary care doctor before beginning any diet regimen is recommended.