Why Almost Everything Dean Ornish Says about Nutrition Is Wrong
Halibutboy Flatface stashed this in Eat drink party
Holy cow, this guy built a diet empire on a horribly flawed experiment with a total of FORTY EIGHT subjects. How do I get into this business?!?!?
You have to give up your belief in science and logic, and give up your conscience too.
The point here is not that Ornish’s diet—a low-fat, whole food, plant-based approach—is necessarily bad. It’s almost certainly healthier than the highly processed, refined-carbohydrate-rich diet most Americans consume today. But Ornish’s arguments against protein and fat are weak, simplistic and, in a way, irrelevant. A food or nutrient can be healthy without requiring that all other foods or nutrients be unhealthy. And categorizing entire nutrient groups as “good” or “bad” is facile. “It’s hard to move the science forward when there are so many stakeholders who say ‘this is the right diet and no other one could possibly be right,’” Bazzano says. Plus, discouraging the intake of entire macronutrient groups can backfire. When people dutifully cut down on fat in the 1980s and 1990s, they replaced much of it with high-sugar and high-calorie processed foods (think: Snackwell’s). If we start fearing protein, too, what will we fill our plates with instead? History tells us it’s not going to be spinach.
It’s possible to cherry-pick observational studies to support almost any nutritional argument.
What’s more relevant to the discussion is this fact: During the time in which the prevalence of obesity in the U.S. nearly tripled, the percentage of calories Americans consumed from protein and fat actually dropped whereas the percentage of calories Americans ingested from carbohydrates—one of the nutrient groups Ornish says we should eat more of—increased. Could it be that our attempts to reduce fat have in fact been part of the problem? Some scientists think so. “I believe the low-fat message promoted the obesity epidemic,” says Lyn Steffen, a nutritional epidemiologist at the University of Minnesota School of Public Health. That’s in part because when we cut out fat, we began eating foods that were worse for us.
Ornish goes to argue that protein and saturated fat increase the risk of mortality and chronic disease. As evidence for these causal claims, he cites a handful of observational studies. He should know better. These types of studies—which might report that people who eat a lot of animal protein tend to develop higher rates of disease—“only look at association, not causation,” explains Christopher Gardner, a nutrition scientist at the Stanford Prevention Research Center. They should not be used to make claims about cause and effect; doing so is considered by nutrition scientists to be “inappropriate” and “misleading.” The reason: People who eat a lot of animal protein often make other lifestyle choices that increase their disease risk, and although researchers try to make statistical adjustments to control for these “confounding variables,” as they’re called, it’s a very imperfect science. Other large observational studies have found that diets high in fat and protein are not associated with disease and may even protect against it. The point is, it’s possible to cherry-pick observational studies to support almost any nutritional argument.
Randomized controlled clinical trials, although certainly not perfect, are better tools for chipping away at causality, and they suggest that protein and fat don’t deserve to be demonized. In a 2007 clinical trial led by Gardner researchers randomly assigned 311 individuals to four groups: One group was assigned the high-fat, high-protein and low-carbohydrate Atkins diet; the second was assigned Ornish’s very low-fat vegetarian diet, which requires consuming fewer than 10 percent of calories from fat; the third was assigned the Zone diet, which aims for a 40/30/30 percent distribution of carbohydrate, protein and fat; and the fourth was assigned the high-carbohydrate, low–saturated fat LEARN (for: lifestyle, exercise, attitudes, relationships, nutrition) diet. The participants all had trouble adhering to their regimens, but all lost about the same statistically significant amounts of weight, and when compared head to head, the Atkins dieters saw greater improvements in blood pressure and HDL cholesterol than the Ornish dieters did.