There have been many articles recently both in the medical and lay press urging patients to take better care of themselves: lose weight, exercise, eat "healthy" foods, stop smoking, don't drink to excess, etc. The problem with compliance with this or any other medical advice (take your prescribed medicine daily, please get a colonoscopy) is that if the advice does not fit in with the patient's mental model of disease, it won't be followed. I always allow 45 to 60 minutes for the first visit, so I can explore with the patient his/her model of disease.
The problem with patients' following any medical advice is that the human brain is designed to react to immediate problems, and not those predicted to happen 20 years down the road. We also have magical beliefs about our health, and sometimes are too eager to follow the latest health fad without examining the scientific data behind the recommendations. We all have heard of the remark made by a Greek mathematical tutor to Alexander the Great : "There is no royal (i.e. shortcut) road to education", but we do not realize that this applies to taking care of ourselves medically, as well.
Without sounding prejudicial, because I have seen many unpredicted beneficial reactions to many treatments (last month an elderly male patient of mine had his shoulder repaired, and afterwards his problems with his prostate disappeared), I must remind my readers that "alternative" medicine is another way of saying "unproven" medicine, although some alternative treatments do work on some patients.
Vegetarianism is an interesting belief. All animal cells need vitamin B-12 to create the nuclei of new cells, and no vegetable cells do. In fact, if you are a strict vegetarian (meaning no milk, fish or eggs, etc.) then you will die from pernicious anemia in 3 to 5 years from lack of vitamin B-12, and may sustain irreversible damage to your brain cells or peripheral nerves before you die. In addition, there are eight "essential" amino acids, in that unless your food contains all eight, you cannot make new protein. All animal meals contain these eight, of course, but no vegetable does. This is why traditional vegetarian meals must contain two different kinds of vegetables: rice and beans, corn and green peas (aka "succotash), etc. Furthermore, autopsy of the oldest human skeletons, when we were just meat-eaters, shows no evidence of tooth decay. Once we started to farm, and eat more carbohydrates, then dental caries appeared in autopsies.
Some examples of past and present beliefs (again I am only saying that there is no rational evidence in favor of a defined belief, not that it is necessarily incorrect):
Frontal lobotomies to cure schizophrenia, induced insulin shock to cure schizophrenia or epilepsy, bleeding to treat various diseases , purgatives to remove "poisons", high colonic enemas to cleanse oneself out, magnets in your shoes or on your belt to cure an aching back, copper bracelets to cure arthritis, staples in the earlobe to reduce appetite, eye exercises to improve myopia, chewing your food 20-100 times before swallowing it, an hour of sleep before midnight is worth two after midnight, a certain number of bowel movements a day or per week is necessary for good health, if you swallow fruit seeds you will grow bushes in your stomach, brown eggs are healthier than white eggs, raw (un-pasteurized) milk is healthier and safer, intravenous chelation therapy to remove harmful metals, removal of mercury fillings to de-toxify your body, fluoridated water is dangerous to your health,-----.
The way to test any of these beliefs on yourself is to alternately follow the advice and then completely ignore it either for one week or one month at a time. In that way you can determine what makes you feel better.
Other beliefs are more subtle. Yes, we all know we should lose weight, but few people believe that losing weight is beneficial enough to one's health to go through the discomfort of actually doing it. We all generally feel better after exercise ("runner's high") due to the generation of endorphins, but rarely do we make exercise part of our regular ritual. Furthermore, if we abstain for two weeks, there tends to be tremendous inertia against restarting exercise. We all believe that cigarettes are harmful, but no one believes that the one they are smoking at this instant will be fatal. We know that exceeding the speed limit is dangerous, but we do it so often that it becomes meaningless to us.
Many men believe that you are sick only if a doctor tells you that you are sick, so if you never see a doctor, then you are never sick. (This is one reason so many men become depressed after a heart attack---their system of denial has visibly failed.) Everyone believes that the less medicine you take, the less sick you are, so most patients try periodically to taper their medicines, often without checking with the doctor. Many patients absolutely refuse to have a colonoscopy, and some even refuse to do the stool- for- blood test. Some men are anxious to have a cardiac stress test, and some absolutely refuse. Meanwhile, many wives come with their husbands into the consultation room to make sure their husbands tell me the truth, and some even come into the exam room. Often a husband comes in asking for a stress test because his wife asked him to. When you dine in a restaurant if you will often hear wives telling their husbands what to eat, how much to eat, and what not to eat---again the man and his wife have different beliefs about food.
What I am trying to say in all the above is that it is generally fruitless to try to argue a patient out of his/her medical belief system, because it is rarely rational. I can sometimes get a patient to try it my way for one month, and then make an informed decision as to whether or not they feel better, but a spouse's medical advice is generally doomed to failure. Sometimes, a patient knows what the "right" medical thing is to do, but for various subconscious reasons just refuses to do it. They even will admit that they "should" do this or that, but they won't. Just recall how difficult it was to get your two-year-old child to eat spinach, and then extrapolate to the refusal an adult can mount.
Finally, please remember Freud's dictum that the ego cannot conceive of its own non-existence, i.e. of its own death.