Originally Published:20040601. Probably the major fault line that separates the old guard in nutrition from the new is the fascinating subject of our hormonal response to food. The old guard insists it has little effect on weight loss and gain (because only calories matter, remember?), while the new guard believes that a program that doesn't take the behavior of hormones into account is doomed to failure. Full disclosure: I think the old guard's nuts. A juvenile, or type I, diabetic is fully capable of eating his parents out of house and home, downing 5,000 calories a day. If calories were all that mattered, he should be getting fat, right? But he doesn't. In fact, he continues to lose weight at an unexplained and alarming rate, which, coupled with copious amounts of urination and unbearable thirst, is an unmistakable sign of type I diabetes. Why doesn't he gain weight? Because his pancreas does not produce enough of one of the most important hormones: insulin. And without insulin, the sugar (and amino acids) in his bloodstream cannot get into the cells and be used for either building muscle or fat. Without insulin, he cannot gain weight. Without insulin, in fact, he will the, which was the fate of anyone unlucky enough to have this disease in the early part of the aoth century, before the role of insulin was fully understood and before it became possible to provide it to those who were missing it. Interestingly, I was recently interviewed on a radio show by my dear but misguided friend Liz Neporent, who is clearly in the camp of the old guard. She said to me: "Look, I simply can't believe this whole theory that insulin has such a big effect on weight. After all, there are dozens of other hormones to consider, why all the emphasis on this one?" That's like saying to a basketball player, "There are so many skills that go into being a well-rounded athlete. Why all this emphasis on how high you can jump?" It's certainly true that many factors need to be taken into account in evaluating all-around athletic ability, but if you're choosing a player for your basketball team, his marathon time or this weight-lifting ability is just not a big consideration. On the basketball court, some skills matter more than others. And while it is absolutely true that levels of other hormones can have a profound effect on weight loss efforts-thyroid hormone, for example, testosterone, estrogen or human growth hormone-on the playing field of weight loss, insulin is the Michael Jordan of hormones. And there is a drug, widely available, completely legal, which you can use right now to modulate your levels of this all-important hormone. In fact, you probably have it in your home this very minute. It's called "food." Look, if food is a drug-and it is-my mission is to teach you how to make it last as long as it can and feel as good as it can. You were not meant to live your life in a body four times the size of the "blueprint," with flagging energy and low self-esteem, suffering from arthritis, asthma, blood sugar diseases, cancer, heart disease, osteoporosis and all the other maladies that have cropped up like weeds in the last hundred or so years. It's your birthright to live out your life in good health in a strong and fit body, with a strong sense of your own worth and purpose and an ability to contribute and give back to the world-not be riddled with angst about not being perfect because you don't look like the heroin-addicted waif-du-jour on the cover of some fashion glossy. And your individual hormonal response to the food you eat is a big player in the weight loss game, not to mention its effect on your mood, your energy and your sense of well-being. Your choice of food determines your body's hormonal response to it. But let's understand how all this works. And in doing so, let's take a look at this hormone insulin and see why it's getting so much attention. Understand this, and a lot of dietary information that you may have been confused about will become clear almost immediately. When you eat a meal, any raeal,_your blood sugar rises. The body knows that it needs to keep blood sugar within a healthy range, so in its infinite wisdom it dispatches the hormone insulin to "escort" sugar into the cells, where it can be used for energy, or, all too often, into the adipose tissues, where it is stored as fat. Insulin is known as an "anabolic" hormone, since it is involved in building up the body, mainly the cells which it nurtures with its periodic delivery of the body's building blocksglucose (sugar), amino acids (protein) and fatty acids (fat). So the job of insulin is twofold. One, to get the blood sugar back to normal. Two, to get the sugar (and the fat and the protein) escorted into the cells, where they can be used for energy or where they can be transformed into something we can store for later use. When this system works well, which it sometimes does, everything is fine. However, in response to a continuous high-carbohydrate, low-fat diet that most of us have been taught is healthy and that also happens to contain a ton of sugar, very little fiber and an awful lot of processed food, that's not what happens at all. What happens is this: We eat a large high-carb meal. Our blood sugar goes skyrocketing. The pancreas says, "Uh, oh, better send in the insulin troops," but now there's so much sugar in the bloodstream that a little bit of insulin isn't enough-we need more to do the job. If you're a sedentary person, the situation is worse. Your muscle cells begin to show some resistance to the effects of insulin. They tend to stop answering the door and essentially begin to sing the chorus ofthat Little Richard song, "I Hear You Knockin' but You Can't Come In!" After a meal, blood sugar stays elevated longer because very few muscle cells will take it in. More insulin is secreted by the poor overworked pancreas in an attempt to get that blood sugar down. Since sugar (and its insulin escort) isn't getting a great reception by the muscle cells, it goes to its second choice-can anyone guess where? Exactly. Insulin and its client, sugar, knock on the door of the fat cells, where they find a big old welcome mat. And meanwhile, look what's happened elsewhere in the body, none of it good: Blood sugar is perennially high, as are circulating levels of insulin (which, incidentally, puts you at risk for a whole cornucopia of conditions that you do not want). When blood sugar and insulin levels rise precipitously, they eventually come down with a crash-and a whole cycle of low and high energy, cravings and weight gain has begun. And, in the bargain . . . We get fat. m.