In the area of diet, we are only asking for fairly modest shifts,

This does very strongly refute the dominant view in the 1990s, that reducing the amount of fat in the diet would spontaneously lead to weight loss. What's happened to the American diet during this low-fat period is, people were given the idea that if they reduced calories from fat, weight would go down. Clearly, that has not happened.

One of the problems with a low-fat diet is that it actually drives down the good cholesterol -- the HDL -- in our blood (and that) ... will probably increase the risk of heart disease,

Even if you do see a small benefit for, say, breast cancer, you couldn't be sure it was due to fat and not due to the fact that the women also increased their fruit and vegetable intake and there was also a small weight loss. I think it's clear this study was a mistake.

With breast cancer, nothing is straightforward. It makes sense for most people to make their dietary decisions based on what it does for heart disease. That's where the data are most strong.

Further adding, “Increased intakes of polyunsaturated fat also probably explain most of the major declines in coronary mortality in the United States, United Kingdom and Australia over several decades.