(CNN) -- Followers of the Paleo Diet may go prehistoric on U.S. News & World Report this week. The publication has ranked the controversial diet last on its "Best Diets Overall" list for 2014.
Each year, U.S. News & World Report asks experts to rank various nutrition plans to help consumers make informed decisions. This year the panel evaluated 32 of the most popular diets.
To be top-rated, a diet has to be relatively easy to follow, nutritious, safe, effective for weight loss and protective against diabetes and heart disease.
First popularized in the 1970s, the Paleo Diet asks people to follow a diet similar to those who lived during the Paleolithic era, between 2.6 million and 10,000 years ago. This means eating like hunters and gathers -- consuming lots of produce and animal protein, while avoiding sugar, grains, legumes and dairy altogether.
"If the cavemen didn't eat it, you shouldn't either," U.S. News & World Report summarized.
The diet has gained a significant following in recent years, especially among the CrossFit crowd. "Paleo Diet" was the most searched diet term on Google in 2013.
Being last on the Best Diets list doesn't mean Paleo is the worst diet ever (the "Cookie Diet" didn't even make the list). But U.S. News & World Report's experts said the Paleo Diet was too restrictive for most people to follow long term, and that it limited some essential nutrients. They also cited a lack of research proving the Paleo Diet's cardiovascular health and weight loss benefits in their ranking.
The Paleo Diet tied for last place on the list alongside the Dukan diet, which is also a high-protein, low-carbohydrate approach.
For the fourth year in a row, the DASH Diet Eating Plan was named the best overall diet. DASH, or Dietary Approaches to Stop Hypertension, was developed by the National Institutes of Health for people with high blood pressure. But it is also effective in lowering cholesterol and reducing a person's risk for heart disease, stroke, kidney stones and diabetes, its website states.
Unlike many diet plans, DASH doesn't cut out or extremely restrict certain foods. Its focus is on limiting daily sodium intake. The meal plan includes three whole-grain products each day, four to six servings of vegetables, four to six servings of fruit, two to four servings of dairy products and several servings each of lean meats and nuts/seeds/legumes.
The diet's only downfalls, the expert panel said, are that it takes some "grunt work" to adhere to, and that it may cost more than a diet based on "processed, fatty, sugary foods."
Following DASH on the best overall list was theTherapeutic Lifestyle Changes Diet, which also was created by the National Institutes of Health. Next in line were the Mayo Clinic Diet, the Mediterranean Diet andWeight Watchers -- all tied for third place. This is the same as last year's ranking.
U.S. News & World Report also published several other lists, including best weight-loss diets, best diabetes diets, best commercial diet plans and easiest diets to follow.
Weight Watchers topped the best weight-loss, best commercial diet plan and easiest to follow lists. Also high on several lists were the Jenny Craig plan and "The Biggest Loser" plan.
For more, visit U.S. News & World Report's Best Diets Rankings.