The World Health Organization says worldwide obesity has more than doubled since 1980. Advocates of one diet say the answer to getting a lean, healthy body lies with our hunter-gatherer ancestors.
In increasingly middle-class economies, where processed snack foods, candies and packaged meals are plentiful, eating a healthful diet can be a bit of a struggle.
One alternative getting attention in the United States is the Paleo diet. It focuses on the natural foods that advocates say humans are genetically adapted to eat: meats, seafood, vegetables, fruits, nuts, seeds, roots and tubers.
The catch? No grains. Only minimally processed foods, limited sugars, few starches, and for the truly devout, no dairy.
Robb Wolf, a former research biochemist and author of The Paleo Solution - The Original Human Diet, explains.
“We evolved as hunter-gatherers over the course of millions of years, and it’s only been the past couple of thousand years, between two [thousand] and 10,000 years, that we’ve really transitioned into an agrarian or agriculture-based way of living.”
Paleolithic humans - who lived more than 10,000 years ago - hunted meat and gathered fruits and vegetables. Wolf says sticking to those foods is healthier than following the diets of modern farming cultures, which include grains.
Sean Beliveau is a believer. The 42-year-old construction contractor says after struggling with other diets, he found success on the Paleo diet.
“As we started to get into it, I lost about 50 pounds [22.6 kilograms] in the first five months on the diet, and kind of stabilized into a lifestyle that is pretty easy to manage and maintain," said Beliveau.
Beliveau says his blood pressure and cholesterol level have dropped dramatically, and his overall health is better.
Wolf says the Paleo diet provides benefits for a number of medical conditions, including Type 2 diabetes and heart problems. And he says eliminating grain from the diet may help ease autoimmune diseases such as rheumatoid arthritis, although there is no conclusive scientific evidence for that claim.
Wolf attributes many of these diseases to the introduction of grains to the human diet. He says that many grain seeds are toxic or hard to digest.
“They tend to irritate the immune system, and rightly so, because this is the reproductive part of the plant," he said. "If they didn’t have some sort of anti-predation chemical in them, then they would just get eaten, and they wouldn’t reproduce.”
But Deborah Jeffrey, a registered nutritionist and dietitian, says that while wheat, corn and other grains may aggravate some conditions, they don’t affect everyone.
“I don’t see any evidence that would say the majority of the population has problems," said Jeffrey. "I think it’s because grains and processed white flour products are things that people tend to over-consume and take in excess calories through, so they just come up with these general statements that they should just be entirely avoided.”
But that could mean people on the Paleo diet don't get enough carbohydrates, vitamins and fiber. That concerns registered dietitian Pat Compton.
“The keys have always been with what we should be eating, are balance, variety and moderation," said Compton. "And with this, the Paleo diet, you really are not getting that.”
Compton says our Paleolithic ancestors didn’t eat grains because they didn’t know the benefits.
Other nutritionists say the Paleo diet can be the basis of a healthful lifestyle, but note that many people don’t stick to the diet long term because it is too restrictive.
However, Robb Wolf says finding substitutes for grains is not difficult. He points to yams, taro and other root vegetables.
“Take a 2,000-calorie diet based around grains, legumes, dairy, and compare that nutritionally with a 2,000-calorie diet built around Paleo foods and it's impossible to get as much vitamins, mineral, anti-oxidants, as what you get from a Paleo-type diet," he said.
In recent years, the Paleo diet has seen increased popularity, particularly among athletic communities. But advocates of this way of eating say it can benefit anyone who is pursuing a healthful lifestyle.