Science writer Gary Taubes has done more than anyone else to deconstruct the Keys mythos and replace it with a more sensible view, informed by better science. I recommend his book, Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control and Disease. It presents more than 600 pages of evidence that lead to these conclusions:

1. Dietary fat, whether saturated or not, is not a cause of obesity, heart disease or any other chronic disease of civilization.
2. The problem is the carbohydrates in the diet, their effect on insulin secretion, and thus the hormonal regulation of homeostasis -- the entire harmonic ensemble of the human body. The more easily digestible and refined the carbohydrates, the greater the effect on our health, weight and well-being.
3. Sugars -- sucrose and high-fructose corn syrup specifically -- are particularly harmful, probably because the combination of fructose and glucose simultaneously elevates insulin levels while overloading the liver with carbohydrates.
4. Through their direct effects on insulin and blood sugar, refined carbohydrates, starches and sugars are the dietary cause of coronary heart disease and diabetes. They are the most likely dietary causes of cancer, Alzheimer's disease and other chronic diseases of modern civilization.

My point here is not to promote meat consumption. I've written here previously about humanitarian and ecological reasons to avoid a meat-centric diet, especially if the meat comes from factory-farmed animals. Instead, my purpose is to emphasize that we would be much healthier as a nation if we stopped worrying so much about fats, and instead made a concerted effort to avoid processed, quick-digesting carbohydrates -- especially added sugars.