self-experimentation as a research device because so many of the most important discoveries came from scientists and doctors who used themselves as test subjects, he says, but I had never before performed a series of trials on my own health. His journey takes him across the United States, where he meets with both long-lived, healthy folk, and health and longevity experts, to learn the secrets of their success.Your Body Was Built for Periodic Cycles of Feast and FamineFasting, it turns out, has a number of health benefits that most people seek: from improved cardiovascular health and reduced cancer risk, to gene repair and longevity.In short, he discovers that part of what appears to be driving the disease process is the fact that were eating too frequently. When youre in constant feast mode, your body actually forgoes much of its natural repair and rejuvenation programming.Its true that severe calorie restriction promotes both weight loss and longevity in animal models, but this kind of starvation diet is not a very appealing strategy for most people.However, newer research shows that you can get most if not all of the same benefits of severe calorie restriction through intermittent fasting, i.e. an eating schedule where you feast on some days, and dramatically cut calories on others.This effectively mimics the eating habits of our ancestors, who did not have access to grocery stores or food around the clock. They would cycle through periods of feast and famine, and modern research shows this cycling produces a number of biochemical benefits. In short, by altering what and when you eat, you can rather dramatically alter how your body operates. And thats great news.Health Benefits of Intermittent FastingFasting is historically commonplace as it has been a part of spiritual practice for millennia. But modern science has confirmed there are many good reasons for fasting, including the following:Normalizing your insulin and leptin sensitivity, and boosting mitochondrial energy efficiency: One of the primary mechanisms that makes intermittent fasting so beneficial for health is related to its impact on your insulin sensitivity.While sugar is a source of energy for your body, it also promotes insulin resistance when consumed in the amounts found in our modern processed junk food diets. Insulin resistance, in turn, is a primary driver of chronic diseasefrom heart disease to cancer.Intermittent fasting helps reset your body to use fat as its primary fuel, and mounting evidence confirms that when your body becomes adapted to burning FAT instead of sugar as its primary fuel, you dramatically reduce your risk of chronic diseaseNormalizing ghrelin levels, also known as the hunger hormonePromoting human growth hormone (HGH) production: Research has shown fasting can raise HGH by as much as 1,300 percent in women, and 2,000 percent in men, which plays an important part in health, fitness, and slowing the aging process. HGH is also a fat-burning hormone, which helps explain why fasting is so effective for weight lossLowering triglyceride levels and improving other biomarkers of diseaseReducing oxidative stress: Fasting decreases the accumulation of oxidative radicals in the cell, and thereby prevents oxidative damage to cellular