Introduction When it comes to health, have you ever noticed how the media have a tendency to focus on the latest scary risk factor, a gimmicky new solution, or the bright and shiny promise of a cure (when there never really is one)? That''s because diet and health advice in magazines and on TV is, for the most part, designed to get us to read the issue every month or tune in to the program every day. The constantly changing news and advice can leave us feeling downright baffled, but it doesn''t bother editors or TV producers in the least. I know this, because I have a bit of insider experience. In addition to my work as a preventive medicine specialist, I have worked as a columnist for national magazines and as a medical expert for national news shows. One evening several years ago, I was preparing a segment about a new diet study for a TV program the following morning. During a phone call with the writers and producers, we were zipping through the content in a very routine fashion- until I shared what I thought the "punch line" should be. At that point, the senior producer, who had been listening silently, suddenly chimed in, "You can''t say that!" "Why not?" I asked. "Because you were on the show last week and you said the same thing," she explained.

"It will be boring if you repeat the same conclusion." "Maybe," I replied, "but it happens that fruits and vegetables are still good for people!" This is hardly an uncommon situation; I''ve encountered it many times in my work. The point here is there''s a constant tension in the media between what''s new and what''s true, what makes for sound science and what makes for provocative headlines or intriguing sound bites. Although I''m sympathetic to the media''s challenge to keep their audience engaged, dressing up dull scientific findings to make them sexier, fresher, or more surprising sometimes changes them to the point where the truth can be very hard to recognize. This phenomenon reminds me of the riveting courtroom scene in the movie A Few Good Men , where Tom Cruise''s character (a Navy lawyer) is grilling Jack Nicholson''s character (a crusty Marine colonel) about whether he ordered a Code Red. At one point Cruise''s character hollers that he wants the truth, to which Nicholson''s character famously replies, "You can''t handle the truth!" The notion that people can''t handle the truth if it isn''t wrapped in a pretty package is prevalent in the world of health and medicine, too. Can you handle it? This is an important question, because if the answer is yes, then you can take control of the master levers of your medical destiny. We can exert incredible power over both the number of years in our lives and the quality of those years.

We can help ourselves sidestep illness and health risks and help our children do the same. We can even untwist the implications of our DNA in our favor. The master levers of your personal medical destiny are truly powerful and within your reach. In the European Prospective Investigation into Cancer and Nutrition (EPIC) Potsdam study, published in 2009, researchers examined four factors- smoking, body weight, physical activity, and diet- among 23,153 German participants, ages thirty- five to sixty- five, and tracked their health effects over the life span. Each healthy lifestyle factor- never smoking, having a body mass index (BMI) lower than 30, performing at least three and a half hours of physical activity per week, and eating a nutritious diet (a high intake of fruits, vegetables, whole- grain bread, and low red meat consumption)- was associated with a decrease in the risk of any chronic disease. Flipping the switch from bad to good on any one of these lifestyle factors was associated with a 50 percent reduced probability of chronic disease. But what was most eye- opening is that participants who had all four healthy factors at the start of the study had a nearly 80 percent reduced risk of developing any major chronic disease. The reduction in diabetes risk alone was 93 percent.

There simply is- and in my opinion, there never will be- a drug to rival that. And to use lifestyle as medicine . well, no prescription is required! It''s important to remember that science is all about the slow accumulation of evidence and the gradual evolution of understanding, which sometimes involves confirming time- honored truths. (Yes, fruits and veggies really are good for us, just like they were last week and will be next week.) If you put too much stock in the latest media report about what is or isn''t good for you or what truly increases or decreases your risk of developing a particular disease, you may end up with a terminal case of health information whiplash. At some point, you may throw up your hands in frustration and tune out the messages entirely, even when they''re valid. Clearly, that''s not the way it should be. Contrary to what common assumptions and the media sometimes lead us to believe, our genes do not determine our weight or future health.

What they do is to tell us about our risks of developing certain diseases. It''s about possibility; nothing is set in stone. Our DNA simply cannot forecast that we will get a particular disease, unless it''s one that''s caused specifi cally by a genetic mutation (such as Huntington''s disease, cystic fibrosis, or sickle cell anemia). We are actually the ones driving the bus on our journeys toward wellness or illness, so don''t blame your genes for the future of your health. Most diseases are not random occurrences but the consequences of the things people do every day. They are the intermediate step between lifestyle habits and infirmity or death. This means that the leading causes of death and disease are largely within our control because they result from what we do or don''t do with our feet, our forks, and our fingers- namely, whether we are physically active, consume a healthy diet, or smoke- on a daily basis. With few exceptions, that is the new rule that''s been established by groundbreaking research- and it is the central premise of this book.

As you''ve just read, there is now abundant evidence that getting just four things right- not smoking, maintaining a healthy weight, being active, and eating well- could reduce the risk of all chronic diseases by 80 percent. That''s right: 80 percent! (There are four things on the list, but by eating well and being physically active, you will set yourself up for a healthy weight- so you really need to focus only on three things, with the final one being not smoking.) It''s a realization that could, and in my opinion should, remake the way we play the game of life, by inspiring us to make better lifestyle choices. If you do it right, you can write a new story for your future right down to the genetic level. To a preventive medicine specialist like me, this is of profound importance, because apathy and fatalism are among the biggest enemies of health and healing. Becoming a doctor was a natural choice for me. My father is a doctor, and I knew I wanted to do something that mattered, that felt challenging and rewarding. During my training, I spent a lot of time trying to figure out what kind of doctor I really wanted to be, and I couldn''t help but notice that roughly eight out of ten hospitalized patients had serious illnesses, all of which could have been prevented by exercising, eating well, or not smoking.

It seemed tragic to me that these people were suffering and shortening their lives- when a more healthful lifestyle could essentially have immunized them against such misery. It was then that the path to my life''s work became clear: I started investigating how a doctor becomes an expert in using lifestyle as medicine and how best to leverage nutrition, in particular, to help people avoid getting sick in the first place. The rest, as they say, is history. I have been an internist and a preventive medicine specialist ever since. I rely on both aspects of my training to take care of existing patients- and to try to help as many people as possible avoid becoming my (or any other doctor''s) patients in the first place! Rewrite Your Future The fact is healthful behaviors create an opportunity to reshuffle the genetic deck in your favor. After all, genes don''t affect your health because they''re there; they represent a recipe for biological material- including specific proteins that turn those genes on or off- that needs to be made in order to set a disease course into motion. You can change the behavior of your genes, essentially dialing their expression up or down, by modifying your lifestyle. Just because you carry a gene that makes you vulnerable to colon cancer or lung cancer, for example, doesn''t mean you''ll inevitably develop the disease.

If you exercise regularly, stick with a healthy diet, avoid smoking, and maintain a healthy weight, you stand a much better chance of never developing those illnesses, even if other members of your family do. There are only so many parts to the human body- we can''t expect to discover new bones or organs- and the same is true of the skills that will save your life and promote better health and well- being. There is a skill set some people have that enables them, in spite of all the conflicting news and opposing societal forces, to stay lean and maintain good health. They weren''t born with this skill; they learned it at some point in their lives, and you can learn it, too. Think of it as an essential tool kit you didn''t even know you needed: Once you have it and you master the use of the different tools, you''ll have the skills for life. An 80 percent reduction in the incidence of all chronic disease would certainly count among the most stunning advances in the history of public health. While it''s unquestion.