Scientific American says that nearly everything Dean Ornish says about nutrition is wrong
I put up a page on this site after reading Dr. Dean Ornish’s recent editorial in the New York Times that blamed Americans’ high rate of obesity on too much fat and protein in their diets. But an April 22, 2015 article in Scientific American (SA) challenges his claims and says that “…the research he cites to back up his op–ed claims is tenuous at best.” In a nutshell, “There’s little evidence to suggest that we need to avoid protein and fat.”
Not only that: “If anything, our attempts to eat less fat in recent decades have made things worse.” The data shows that Americans have been eating more of everything, but that the percentage of calories from fat and protein has decreased while the percentage from carbohydrates has increased. The data is apparently supplied by the USDA Agriculture Fact Book 2001-2002. (A quick web search did not yield a more recent version.) The SA article quotes Lyn Steffen, a nutritional epidemiologist at the University of Minnesota, who sees evidence that the “low-fat message” has induced us to eat more “…foods that were worse for us.”
The SA article cites a research study conducted at Stanford, where Ornish is associated as well, that consisted of a clinical trial of four types of diet: the Atkins diet, the Zone diet, the Ornish diet and the LEARN diet. I quote in full the conclusion from the study abstract below:
In this study, premenopausal overweight and obese women assigned to follow the Atkins diet, which had the lowest carbohydrate intake, lost more weight at 12 months than women assigned to follow the Zone diet, and had experienced comparable or more favorable metabolic effects than those assigned to the Zone, Ornish, or LEARN diets [corrected] While questions remain about long-term effects and mechanisms, a low-carbohydrate, high-protein, high-fat diet may be considered a feasible alternative recommendation for weight loss.
The magazine article also examines Ornish’s claims for the success of his recommended diet and points out several problems with his study. One is that the people following his diet also made other significant life style changes such as quitting smoking and exercising, that could be equally responsible for the observed results. Another is that his diet also eliminated refined carbohydrates. This could be just as responsible for his results as eliminating meat protein. According to the magazine there were only 48 participants in Ornish’s study. To me that is a very small sample upon which to base such a dramatic conclusion.