Should You Eat a Low Fat Diet?
I have written before about how poorly the news media covers science. Today there is a very important result on low-fat diets being reported in the Washington Post and the New York Times. The studies show that low-fat diets do not protect against heart attack, stroke, or cancer. Many people are quite disappointed by this result, but facts are what count not what people want. The point of the study is that a low-fat diet does not provide health benefits. Here is a quote from the top of the Washington Post article.
“Based on our findings, we cannot recommend that most women should follow a low-fat diet,” said Jacques Rossouw of the National Heart, Lung and Blood Institute, which funded the $415 million study.
But later there is this contradictory statement.
Willett and other researchers fear that the findings will leave the public skeptical about all health advice, or will be misinterpreted to mean that diet and lifestyle are unimportant. A large and convincing body of evidence shows that eating a diet rich in fruits, vegetables and whole grains and low in saturated and trans fats; avoiding smoking; exercising regularly; and maintaining an appropriate weight have a powerful effect on health, they said.
Can these two statements be resolved? I have a guess that they can, but it is just a guess. If the studies controlled for body weight then there could be an indirect effect. If somebody eats a high fat diet but maintains a healthy weight then she is not harmed by the diet. There may not be anything intrinisically dangerous about fats, but they may make it easier to gain weight which is harmful. Why do I beleive the studies controlled for body weight? It is good science to try to control all but one variable. Here the variable is the fraction of fat in the diet.
If my guess is true the articles have failed to make the important point of the studies.