Adherents to Paleo diet find weight loss success by eating like our ancestors

Low-carb diets like Atkins and South Beach have come in and out of fashion for years, but the latest reaches far back into human history for its inspiration.

"Paleo people joke that it's the fad diet with the longest life," says Melissa Joulwan, an Austin writer who transitioned to a Paleolithic diet a few years ago after a lifetime of struggling with her weight despite consistent exercise and following traditional low-fat, high-carb diets.

The Paleo concept is simple: Eat like our ancestors did in the millennia before agriculture, which means no grains, dairy, processed foods, sugar or legumes.

Before agriculture, hunters and gatherers ate meat and plants that didn't require processing to eat, but thousands of years later, grains and processed foods have become the foundation of the American diet. Manufactured foods, especially those based on flour like pasta and bread, are inexpensive, but anything made from grains, including corn, lead to a spike in blood sugar and can damage the insides of the intestines, say proponents of gluten-free diets, which are certainly not limited to people who fall in the Paleo camp.

"The evidence to support eating grains is underwhelming," says Michael Roussell PhD, a Livestrong.com adviser, citing a recent Harvard study that found that, contrary to what we've been trained to believe, simple sugars and refined grains are more detrimental to our health than animal fats. "Just about everybody can benefit from eating less carbohydrates because we're often not eating the best types."

Vegetables and fruit contain plenty of carbs and fiber, and the carbohydrates are easier to digest and don't raise your blood sugar like the starchy ones in white potatoes, rice, corn and other grains.

But when you make a switch from a majority-grain diet to one of mostly animal fats, proteins and vegetable carbs, how your body processes those fats changes, too. "The less carbs you eat, the more saturated or animal fat you can eat," Roussell says. "It changes how your body metabolizes lipids."

When Joulwan first started looking into Paleo diet after hearing about it through her CrossFit workout group, she had a hard time getting past the conventional mind-set that fat is bad.

"When I first heard that half my (calories) would be from fat, I almost had a heart attack," she says. Just like our bodies need fat and salt to function, our bodies need cholesterol, too, and the lean protein and nuts consumed in a typical Paleo meal contain healthier unsaturated fats and low levels of saturated fats.

But as Joulwan slowly started changing her diet — before going fully Paleo she eliminated grains for a year and then took out dairy for another year even though she doesn't have allergies or intolerances — she started losing weight she'd been holding on to for years and realized that almost everything she thought she knew about food and nutrition was wrong.

"Your body doesn't see the difference between a potato, a slice of white bread or a Snickers bar because the sugar is perceived by your body in the same way," she says. "Any grain in its evil little heart is a sugar."

Like with any diet, cutting out sugar seems to be one of the hardest steps, and if you are particularly addicted to sweets, make sure you don't swap candy for candy-sweet fruits. "Fruit sugar is OK as long as you've broken your sugar demon," Joulwan says.

It's the same thing with stevia, honey or other natural sweeteners: A body that is conditioned to eat sweet food will continue to crave sweet food.

Joulwan, a founding member of the Texas Rollergirls whose book about the experience, "Rollergirl," was published by Simon and Schuster almost five years ago, started blogging in 2008 about her recipes and Paleo discoveries on The Clothes Make the Girl (theclothesmakethegirl.com). She's persuaded both her father and a close friend to switch to a Paleo diet, and both of them have lost more than 60 pounds each.

Over the past year, she's compiled more than 100 recipes for her first cookbook, "Well Fed: Paleo Recipes for People Who Love to Eat," which will be available in paperback on Amazon.com and as a PDF on her site in early December.