11/20/2011 11:22 am ET Updated Jan 20, 2012

Traditional Cuisines vs. Full Caveman Diet

Lately I've been seeing a lot of clients under the sway of yet another new diet trend: the Paleolithic diet. This is a diet plan that involves eating like it was the year 8,000 BCE, meaning lots of meat and fish, plenty of root vegetables, nuts and berries, but no dairy, no sugars and, most problematically, no grains. Now, I am not a fan of eating processed food, but I've seen this diet distorting people's relationship to what they eat, and to their own appetites, and it's troubling.

Recently, I began seeing a client whose trainer had told her to give up carbohydrates. He'd told her to stop eating bread completely, and even made her feel guilty for eating a potato! She came to me because she was fatigued -- she had actually fainted at one point -- and she still hadn't dropped a pound. I asked her what she'd most like to eat. She said she wanted nothing more than to eat a sandwich. I told her there was no reason she shouldn't eat sandwiches if she wanted them. A week later she returned, two pounds lighter and having eaten only one sandwich. "Once you gave me the permission to eat the sandwich," she said, "it relieved the pressure on me -- I felt so liberated just knowing that you'd given me the OK." It turned out that that set her free to control her own eating. "I thought I needed the sandwich," she said, "but once I could have it, I realized I didn't really need it after all."

I see many clients like this lady. Many have been advised by fitness trainers that they need to follow one diet or another. Some of this is novelty -- trainers, like many people who see clients, are looking for new things to try, and ways to change things up. And not all of aspects of the Paleo diet are bad -- for example, if done properly it involves hours per day of movement, based in the two most basic forms of exercise, walking and weight-bearing. But the fact is, you don't live like Paleolithic man. Just as you unfortunately probably don't have hours and hours per day to spend in constant motion, you also don't live in a world without grains. In fact, many healthy diets -- a traditional Mediterranean diet, a modern vegan diet -- are organized around grains. What they have that our current eating habits don't is portion control.

Go back to my conversation with my client. She ate a sandwich, and she lost two pounds. The key element was a sandwich. She ate what she wanted, but she ate it in moderation. In fact most traditional diets -- Italian, French or my native Peruvian -- eat a full range of foods, but in smaller portions. If you eat pasta in an Italian restaurant in Italy, for instance, you will most often be served a small plate, with perhaps a third as much pasta as you would be given in an American restaurant. But it is plenty for a single meal. And like my client, if you give yourself permission to eat what you want -- as long as it is real food -- you may find that you are able to eat less of it.

For myself, I am a food lover and so glad to be living in the 21st century, when, unlike Paleolithic man, we have access to all the amazing cuisines of the world. From French to Italian to Peruvian to Thai -- you name it, I love it. I celebrate food and love to eat! You should give yourself permission to do the same. Just remember that, like grains, moderation is a key part of those great traditional diets.

Manuel Villacorta is a registered dietitian in private practice in San Francisco, Calif. He is a national media spokesperson for the American Dietetic Association and the founder of Eating Free.