Dean Ornish, M.D.

The Diet War: Low-Fat vs. High-Protein

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The Diet War: Low-Fat vs. High-Protein

Dean Ornish, MD, is founder and president of the non-profit Preventive Medicine Research Institute and is Clinical Professor of Medicine at the University of California, San Francisco.

Moderator: Welcome, Dr. Ornish. An article in The New York Times suggested that the high-protein/low-carb diets such as the Atkins diet are gaining converts in the medical community after years of rejection. You felt strongly enough about this article to respond with an op-ed piece. Can you tell us a little bit about that?

Ornish: I did. I’m concerned that many people may be discouraged from making changes in diet and lifestyle that we have proven can be life saving for them. Below is the editorial:

In Woody Allen’s movie “Sleeper,” a man wakes up 200 years in the future to find that science has proved deep-fried foods to be healthy. Is the future here already?

By now, many Americans are thoroughly exasperated by the seemingly contradictory information in the press about what a sound diet is. Lately, I hear many people say, “If the doctors can’t make up their minds, I’ll eat whatever I want and quit worrying.”

That would be unfortunate. Science can help people distinguish what sounds good from what’s real. Nowhere are the claims more conflicting than in the area of diet and nutrition. Unfortunately, this is an area where misinformation can make a huge difference to an individual’s health and well-being.

The high-protein diet (which is almost always high in fat), for example, has become very popular; just about everyone knows someone who has lost weight on this kind of diet. Given the American epidemic of obesity, isn’t that a good thing?

Not necessarily. You can lose weight with fen-phen, too, but that doesn’t mean it’s good for you. When you go on a high-protein, high-fat diet, you may temporarily lose weight – but you may also mortgage your health in the process. The only peer-reviewed study of the effects of a high-protein diet on heart function found that blood flow to the heart actually worsened and heart disease became more severe.

But high-protein diets help people lose weight because they are based partially on science, which is what makes them seductive. The high-protein advocates are right when they say that people in the United States eat too many simple carbohydrates like sugar, white flour, and white rice. These foods are absorbed quickly, causing blood sugar to spike, which in turn provokes an insulin response that accelerates the conversion of calories to fat. There is a clear benefit to reducing the intake of simple carbohydrates, especially to people who are sensitive to them.

So the diagnosis is correct: we are eating too many simple carbohydrates. But the cure is wrong. The solution is not to go from simple carbohydrates to pork rinds and bacon, but from simple carbohydrates to whole foods with complex carbohydrates like whole wheat, brown rice, and fruits, vegetables, grains, and legumes in their natural forms.

These foods are naturally high in fiber, which slows their absorption, preventing a rapid rise in blood sugar. Fiber also fills you up before you eat too many calories, whereas you can eat large amounts of sugar without feeling full. Best of all, these foods contain at least 1,000 substances that have anti-cancer, anti-heart disease, and anti-aging properties.

For the past 25 years, my colleagues and I have conducted a series of randomized studies demonstrating that this whole-foods diet can reverse the progression of even severe heart disease in most people. These results have been published in the leading peer-reviewed medical journals. On average, our patients lost 24 pounds and kept more than half of that off for at least five years.

We demonstrated in hospitals throughout the country (including places where we were told that gravy is a beverage) that most heart patients were able to safely avoid bypass surgery or angioplasty by following this diet combined with moderate exercise, stress management techniques, and participation in support groups. Medicare is now paying for 1,800 patients to go on this diet. Recently we found that this program may stop or reverse the progression of early prostate cancer as well. The more closely people followed the diet, the more their heart disease reversed and the lower their prostate-specific antigen, a marker for prostate cancer, became.

It’s not that fats are bad; we just eat too much of them. Fish oil and flaxseed oil are very good for you because they provide the kind of fatty acids that can substantially reduce the incidence of sudden cardiac death and may help prevent some forms of cancer, but you only need a few grams a day. And because fat has more calories per gram than protein and carbohydrates, when you eat less fat, you consume fewer calories without having to eat less food.

Science can help us sort out conflicting claims. Researchers now are studying the effects of high-protein diets. It would be wise to wait for these results rather than discouraging people from making dietary changes that have been medically proved to be so beneficial.

Moderator: So your argument isn’t that the diets don’t work, it’s that no one knows if they are safe in the long run?

Ornish: It is more than that. When you go on a high-protein diet, you may be mortgaging your health in the short run and the in the long run. Studies have shown that blood flow to the heart improves on a low-fat diet rich in complex carbohydrates but worsens on an Atkins-type high-protein diet. When you eat a diet that is predominately complex carbohydrates, you get all of the weight-loss benefits of a high-protein diet and then some, since you don’t provoke an insulin response, and you are eating foods that are much less dense in calories. Fat has nine calories per gram, whereas protein and carbohydrates have only four, so when you eat less fat you eat fewer calories without having to eat less food. And instead of mortgaging your health you are enhancing it. Some people are able to lose weight by smoking cigarettes, but that is not the best way to do it.

Member: So they are not even OK for a short time to lose a few pounds quickly in order to motivate yourself?

Ornish: You can lose a few pounds quickly in a way that will enhance your health. The only reason you may lose a little more weight on an Atkins diet in the first few days is that your body is peeing out (diuresing) a lot of toxic substances. You may lose a little more water weight, which really doesn’t count anyway. Dr. Atkins has never published any articles in any peer-reviewed journals to validate his claims, whereas we have published in all the peer-reviewed medical journals. I’d love to be able to tell you that eating bacon and pork is good for you, but they are not. I eat high-fat foods on occasion, but I don’t delude myself into thinking that they are good for me.

Member: So, how much protein do we need in our diets and what are the best ways to get it and stay low fat?

Ornish: Most people get too much protein in their diet, which may put a strain on their liver and kidneys and hasten illnesses such as osteoporosis. If you eat a good assortment of fruits, veggies, greens, beans, and soy products, perhaps supplemented with fish, you will be getting plenty of protein but you won’t be getting many of the toxic substances such as cholesterol, saturated fat, and oxidants, which often lead to heart disease, cancer, and other illnesses.

Member: How has the high-protein diet gained so much popularity if it is so risky?

Ornish: It is easy to sell books and magazines by telling people what they want to hear. Many people want to believe that bacon and sausage are good for your heart, but they are not. As I wrote in the editorial, the high-protein diets are based on a half-truth. People in the U.S. eat too many simple carbohydrates, which gives them a double whammy. They eat a lot of calories that don’t fill them up and they are more likely to convert those calories into fat. Why? Because when you eat a lot of simple sugars, they get absorbed quickly. This causes your blood sugar to zoom up, which causes your pancreas to secrete more insulin. Insulin lowers your blood sugar but also converts calories into fat.

So there is some benefit to reducing the intake of simple carbohydrates. However, the goal is not to go from simple carbohydrates to pork rinds but to whole foods, such as fruits, veggies, greens, and beans, along with brown rice and whole-wheat flour. These are rich in fiber, which slows the absorption so your blood sugar does not zoom up and your pancreas does not make too much insulin. So, you get the benefits of a high-protein diet without the harmful effects.

I was interviewed by Josh Mankiewicz for Dateline NBC. He says that he lost 50 pounds on an Atkins diet and has a steak every evening for dinner. “How bad could it be?” he asked. I questioned him and he acknowledged that before, he was eating french fries, fried onion rings, cheesecake, salad dressings, and at least five soft drinks per day, everyday, none of which he now consumes, plus he is now exercising every day. I explained that he lost the weight not because of the steak but despite it, because he is no longer consuming 2500-3000 calories per day that he had been eating before. He replied that he needs the steak to avoid eating the other stuff, which is a little like someone who smokes five cigars instead of two packs of cigarettes. It is a better choice but it is still not good for you. As I mentioned, I would love to tell you that eating steak is good for you, but it is not. Hey, don’t shoot the messenger. (There is no Santa Claus either, but you did not hear it from me.)

Member: I hear so many people talking about not eating rice, breads, pasta, and such. I have always thought that it’s not that these foods are bad for you; it’s what you put on them. Is that right?

Ornish: It can be both. It is better to avoid white rice, white flour pasta, and white bread for reasons we talked about earlier. When you go from whole-wheat flour to white flour you remove the fiber and bran that are so beneficial. Fiber slows the absorption of carbohydrates, as we discussed earlier, but you don’t get an insulin response. Also, when you eat a lot of fiber you get full before you get too many calories. In contrast, you can consume virtually unlimited amounts of sugar without getting full. It is also true that what you put on these can help you gain weight. For example, if you put two tablespoons of olive oil on your pasta it gives you as many calories from fat as two scoops of Ben & Jerry’s ice cream. One of the easiest ways to reduce calories in your diet is to consume less oil and less sugar.

There is no mystery in how to lose weight: you burn more calories by exercise, and/or you eat fewer calories. You can eat fewer calories by eating less food, which is why you can lose weight on almost any diet. It is hard to keep the weight off by doing it this way because you get hungry when you eat less food. Instead, when you eat less fat you eat fewer calories without having to eat less food. So, you can eat whenever you are hungry, until you are full, and still lose weight and keep it off without hunger and deprivation.

Member:So can a type 1 diabetic eat complex carbs without worrying about high blood sugar levels?

Ornish: Type 2 diabetics often can reduce or discontinue insulin by eating this way under their doctor’s supervision. There is more variability with type 1 diabetics, who have a different physiological process. However, we have worked with many type 1 diabetics who have improved their blood sugar control by reducing the intake of simple carbohydrates and increasing complex carbohydrates. Also, one of the major complications of diabetes is heart disease and the diet I recommend has been proven to reverse heart disease in most people. Which means it probably works even better to help prevent it.

Member:You say that when you eat less fat you eat fewer calories. That isn’t always true. I have seen plenty foods that are low in fat but high in sugar and therefore high in calories, right?

Ornish: You are absolutely correct. The goal is to eat less fat and less sugar. One of the main reasons why people may gain weight on a low-fat diet is because they eat a lot of fat-free products that are high in sugar, such as frozen yogurt, Snackwell cookies, and so on.

Member: Is there any truth to the claim that unsaturated fats are good for the body?

Ornish: I don’t think so. And there is some evidence that polyunsaturated fats may be harmful. The goal is to try to reduce total fat consumption. You need some fat in your diet but you only need about 20-25 grams per day and many people eat much more than this. Fish oil and flaxseed oil can be protective. For more information on recommended supplements please go to my website at WebMD, which you can also reach at There are lots of gourmet low-fat recipes that are available for free, as well as many other resources.

Thank you so much for your interest, I hope this has been useful.

Moderator: Unfortunately, we are out of time. Thanks for joining us, members, and thanks to Dean Ornish, MD, for being our guest. Sorry we couldn’t get to all of your great questions. For more information, visit the Dea n Ornish, MD, Lifestyle Program here at WebMD and his message board, Dean Ornish: Heart-Healthy Living, as well as our other weight-management boards, including Diet: Weight Loss, with Kelly Brownell, PhD and Diet: Find a Weight Loss Buddy.