Food differs from medicine, only in the intensity of the delivery process. In the short-term most foods are harmless. Your body is well able to cope with over-eating, or over-drinking, if that happens occasionally. However, if we choose our diet badly, firstly, your body adapts and tries to compensate. When we continue that practice over many years, the body's effort to cope is likely to cause inflammation, and slowly that is likely to become a "lifestyle disease."
Because your diet is controlled by you, it gets very little attention. You can only successfully control your diet, if you yourself have good knowledge. Otherwise you live in blissful ignorance until something happens to your life to force you to take notice. You can significantly change your life by changing your diet. There is much to learn, so start slowly. 50 years of prejudice and misinformation, is not easy to overcome.
If you are going to learn about the chemistry of your food, and understand how it affects your body, you'll need to keep notes, and you'll need to experiment for yourself. There is a practical way to do this, making small changes, and building routines for planning meals, and eventually for changing your lifestyle.
You must not assume that dieticians and doctors are good authorities about your diet. So much has changed in the last 10 to 15 years, and because of that the tide of change seems to be running even faster.
Ancel Keys, almost single handedly, created the basis for our current obesity epidemic. He was helped along by a political desire to build a strong market for American corn and wheat, and a failed politician's need to be seen to be doing something really "great" (Senator George McGovern, after his failed bid to be President), in this case, to reduce the rising level of heart disease in America.
Everybody KNEW, what a healthy diet was, and how to prevent heart disease. Or so we were told. Modern medicine would save us all. So here are the failed "solutions": President Eisenhower's Heart attack: The Framingham Heart Study: The Anti-Coronary Club: Multiple Risk Factor Intervention Trial: The Women's Health Initiative. That brings us up to 2006, and "the answer" seems to be, that we don't KNOW, at all.
That is a great step forward. When you don't know you can begin to look for what you've "lost". In fact, when you do that, many new possible solutions pop out of the woodwork. Like the Ketogenic Diet, abandoned by researchers in the late 1920's.
When you don't know the answer, real science can finally overcome political dogma and prejudice. Dr Vilhjalmur Stefansson, Dr George Mann, Dr Weston Price, Dr Fred Kummerow, Dr Robert Atkins, and more recently, Dr Stephen Phinney, battled for years against the prejudice that "we already know" the answer. They all tried to show that Ancel Keys was wrong. We live with that misdirection of nutrition "science" today.
A large number of people are still taking statins to reduce their LDL-Cholesterol. Why? The science says that the side effects are much worse than any possible benefit. Type 2 diabetes is increasing at epidemic levels. Why? With a good diet, the need for additional insulin can be reduced and often eliminated. Too many people are obese. Why? Getting your weight under control is possible if you are well informed. Later in life cancer and Alzheimer's disease threaten to disable many of us, but new science seems to show that by diet alone Alzheimer's can be avoided.