Dr. Dean Ornish on the "myth" of high protein diets

Low-fat versus low-carb? The diet debate is not that simple, says Dr. Dean Ornish, whose own diet plan was ranked #1 for heart health by U.S. News and World Report. And while meat-centric Paleo diets are having their moment, he's warning they could cause health problems down the road.

Ornish, a clinical professor of medicine at the University of California San Francisco, weighed in on the latest diet trends and controversies in a New York Times op-ed Monday, "The Myth of High Protein Diets."

He raised concern about the recent decision by a federal nutrition panel to ease recommendations on dietary cholesterol -- a policy shift that had bacon lovers cheering. "Alas, bacon and eggs are not health foods," Ornish wrote.

"The debate is not as simple as low-fat versus low-carb. Research shows that animal protein may significantly increase the risk of premature mortality from all causes, among them cardiovascular disease, cancer and Type 2 diabetes. Heavy consumption of saturated fat and trans fats may double the risk of developing Alzheimer's disease."

On "CBS This Morning," Ornish said it's important to focus not just on short-term weight loss, but on a diet's role in long-term health -- and he says cutting down on animal protein is key.

"It's true, you can lose weight on these high-animal-protein, Atkins-type diets, but you're mortgaging your health in the process," he said. "It's not even low-fat versus low-carb. There are good carbs and there are bad carbs, there's good fats and bad fats. But the animal protein itself seems to make a big difference. And the more animal protein, particularly red meat, you eat, the more likely you are to get sick from all kinds of different things."

Eating what Ornish described as a "whole-foods, plant-based diet," heavy on fresh fruits, vegetables, whole grains, legumes and soy products, helps keep the arteries in the heart free of plaque buildup. Those are many of the same foods emphasized in the Mediterranean diet, which studies suggest can lower the risk of heart disease and even slow aging.

By contrast, he said, what happens "when you eat a lot of animal protein, particularly red meat, an Atkins-type diet, is that your arteries are more clogged."

He points out that eating a high-protein diet doesn't have to mean gorging on meat. Instead of a steak or burger, you can get protein from soy products, beans, yogurt and other foods. "You're going to get all the protein you need, but you're not getting the bad stuff that makes you sick," he said.

And he urged would-be dieters not to get discouraged by the occasional slip-up. "What matters most is your overall way of eating and living," Ornish said. "So if you indulge yourself one day, it doesn't mean you cheated or you're bad, just eat healthier the next. You don't have time to exercise one day, do a little more the next. You don't have time to meditate for an hour, do it for a minute. Whatever you do, the more you change, the more you improve at any age."