The number of diets out there is legion. Staggering. Bewildering. There are so many, no one can possibly know them all, and no one can possibly be expected to understand which one will actually work for them. The key (and we mean this literally - what you are about to read is The Key) to all dieting is understanding how your body handles the food you eat. After all, it isn't food that makes you lose or gain weight; it is what your body does or doesn't do with the food you eat. What really drives weight loss is understanding how your body handles food and adjusting your food intake accordingly. What we need to do is not "go on a diet," but rather "change our diet." When we understand how our bodies handle the food we eat, it is incumbent on us to adjust our eating habits accordingly. So in this book, when we talk about diets, we are talking about everything you eat from now on...not some specialized meal plan that you're going to do for the next 8 weeks until you reach your weight loss goal. Let me say this a slightly different way: your present diet got you into the place where you are seriously considering reading this book. Unless that diet changes, permanently, you are not going to change your weight or health over the long term for the better. Do what you want "to lose weight," but if you don't change what you eat permanently, so that it works with your body's own biology, you are logically doomed to find yourself right back here reading this again. In this book, we are going to strongly recommend a lifestyle change. Anything short of that is pointless. Temporary measures to achieve weight loss are just that, temporary. We see no value and actually a significant downside to simply losing weight for the short term only to gain it all back, plus a bit more. Not only is future weight loss more difficult, there are deleterious effects on your body and its me- tabolism. It is important that you learn about your physiology and metabolism, and learn about how they work with the food you eat. The goal is to gain a better knowledge of the interaction of food with your body, before you make some life altering decisions. After that you can make an informed, knowledgeable decision with the long view in mind. Our perspective, as you'll see, is skewed to the low carb, ketogenic end of the spectrum. For us, the science and clinical experience in treating thousands of obese patients validates that a ketogenic diet outperforms all others, has the best outcomes, the longest lasting results, requires the least energy to maintain it, and has the best long term health outcomes. But we are going to try to present all your options in a fair and unbiased way. So let's get started. We will look at your body's physiology as it relates to obesity and eating. We will look at food types (there's simplicity there, too, believe it or not) and what each does in your body. And we will look at how you actually eat. We promise you this will be simple, easy to understand, and straight forward. There are no food eating plans, no diet stages, no excess of rules and regulations. We are just going to point you in the right direction, equipped with the right information, and make you cognizant of the appropriate principles to make good, sound lifestyle choices.