For nearly all my adult years (>50), I've been told to eat what was recommended to be the most healthy foods and avoid the "bad guys". No to whole milk. No butter. No red meats. No eggs. White poultry meat only. Eat lots of grains and carbohydrates.
We've been duped into believing that eating fat makes you fat, and that a high fat diet increases cholesterol numbers which in turn leads to heart diseases. No proof, just common sense. For 50 years the American Academy of Pediatrics has insisted that "A low fat diet should be asumed right until proven wrong." (And that includes infants!) Ever since the USDA first recommended a low-fat diet in 1980, the rates of obesity (U.S.) has increased steadily. They still repeat the mantra, "healthy diets are higher in carbohydrates".
Most of the "evidence" has been make-believe. There has been a "selection bias" in trying to show a relationship between high fat--bad health. There has been no clinical (i.e., scientific) trials to prove such relationship. What has been shown is the lower ones cholesterol is, there's a greater chance of getting gallstones, colon cancer, strokes (2-3 times), and being depressed (with increased suicides).
My eyes have been opened by reading The Big Fat Surprise, by Nina Teicholz. She has methodically reviewed all the studies, books, and articles, analyzing the information and results leading to where we are today. Here's her concluding summary:
"If, in recommending that Americans avoid meat, cheese, milk, cream, butter, eggs, and the rest, it turns out that nutrition experts made a mistake, it will have been a monumental one. Measured just by death and disease, and not including the millions of lives derailed by excess weight and obesity, it's very possible that the course of nutrition advice over the past sixty years has taken an unparalleled toll on human history. It now appears that since 1961, the entire American population has, indeed, been subjected to a mass experiment, and the results have clearly been a failure. Every reliable indicator of good health is worsened by a low-fat diet (my stress). Whereas diets high in fat have been shown, again and again, in a large body of clinical trials, to lead to improved measures for heart disease, blood pressure, and diabetes, and are better for weight loss. Moreover, it's clear that the original case against saturated fats was based on faulty evidence and has, over the last decade, fallen apart. Despite more than two billion dollars in public money spent trying to prove that lowering saturated fat will prevent heart attacks, the diet-heart hypothesis has not held up."
In my own personal family history, my mother faithfully followed the low-fat guidelines. She died of peritoneal cancer at age 83. My sister has been diabetic all her adult life, survived breast cancer, and has been a vegan (no animal products) forever. Hmmm. My father, on the other hand, has pooh-poohed all the recommendations and is still healthy and alert at nearly age 97. Excuse me while I go grocery shopping!
PS: Big business food industry has for years persuaded us to use American grown vegetable oils. They've lobbied hard to have us abstain from olive, palm, and coconut oils which are so much better for us. The book discusses that issue in detail. Read it!