"You are what you eat" is one of the most commonly-recognized sayings in modern American culture. I can see the truth to it--we certainly want to ingest substances that contain good nutrients and powerful energy reserves, and can be processed by our bodies cleanly and efficiently without causing hardship or draining our bodies resources through the digestive process.
Green, leafy vegetables, low carb/sugar/meat/fat/cholesterol, fresh, water-dense, nutrient-rich, mineral-rich, and little to no processing, are all commonly agreed upon principles of a healthy diet. There are many variations, of course: low-fat, low-carb, no-carb, vegetarian, vegan, raw food, Paleo, etc. etc. And there people who follow each of these variations at levels ranging from moderate to extreme.
While we can find healthy, fit, vibrant individuals in each corner of the diet map, however, we can also find their unhealthy counterparts in all of those same corners. Quite obviously, therefore, diet is not the whole story when it comes to physical health.
So where does that leave us? Well there is one very logical answer that comes to mind immediately when running a mental search on factors that influence heatlh: exercise. Of course! Right? Yes, but not completely. Still unhealthy people in those same corners who exercise religiously.
So diet is important, yes. Exercise is important too. Oh, and yes, let's not forget about SLEEP. But even with sleep, we still don't have the whole picture quite yet. Even with all of those factors in our favor, we still have unhealthy people in our corners.
What's missing? Ironically, the person who really answered this for me is David Wolfe--one of the most (if not the most) well-known, knowledgeable, and charismatic advocates of the raw, vegan diet (you eat nothing that is cooked or contains animal products--or as little as possible in either of those categories). "You are what you eat" is a quote that he often begins his talks with, and regardless of whether you agree with his food philosophy, most of us agree with that general statement.
I'll make the disclaimer here that, although I have attempted to steer myself in the direction of the "raw food diet" and I do believe that it can have tremendous health benefits, I am not a raw vegan. I'm not even vegetarian. However, David did make an assertion in talk that I listened to that really hit home with me; he said that the number one factor one most important factor in a person's overall health is... relationships.
I would generalize that a bit and say that the third factor (on top of diet and exercise, and aside from external factors such as air pollution or a penchant for taunting wild bears) is mental and emotional well-being--or, in short, happiness. (I would then say that our relationships with others and with ourselves are at the root of every other factor that affects our mental and emotional well-being, such as money....)
Now it seems that being healthy is getting rather complicated. However, there may be an outlook that makes it simpler again: what if one major factor could steer the other contributing factors in the right direction? What if they were connected in some way?
What if... managing our relationships in a way that makes us happy were to also cause us to choose healthier food options, to feel more motivated to exercise, and to sleep better at night? What if our thoughts and emotions affect our lifestyle choices and habits?
Can our moods actually drive our decisions on what to eat, for example? (Hmmm... Where did the phrase "comfort food" food come from? Who invented the concept of gorging one's self on a carton of Häagen-Dazs to sooth a broken heart?) Perhaps there are too many books, articles, blogs, shows, and classes out there that are focused on how and what to eat. Perhaps we already have general idea of what's good for us and what isn't. (I would even argue that our own intuition can often be our best guide for what to eat at any given moment.) I think what we need to focus more on are the factors that drive our food choices; what does it matter what we should be eating when our thoughts and emotions are leading us in a different direction?
Then think about all of the happy people who live long and healthy lives while carrying on lifestyle habits that are commonly known as damaging to our bodies; think of your friend's great uncle who lived to be 105 and drank a whiskey on the rocks, smoked two cigars, and ate bacon for breakfast every day for the last 80 years of his life. Dig a little deeper, and you may find that it probably wasn't the bacon breakfast that kept your friend's great uncle alive for all of those years; you'll likely find something even better about his life to emulate. (Unless bacon breakfast lies at the core of your mental and emotional well-being, of course....)