Like the other low-carbohydrate diets, the Protein Power regimen is based on the idea that controlling the level of insulin, "the master hormone of human metabolism," helps regulate blood pressure, cholesterol, triglycerides, and fat storage. Researchers have long known that carbohydrates cause the body to produce insulin and that high levels of insulin inhibit the breakdown of fatty deposits in the body. In contrast, low intake of carbohydrates keeps insulin levels low, forcing the production of a counterbalancing hormone, glucagon, which seeks energy from the body's supply of stored fat. Therefore, one loses weight. Do this long enough and the fat seems to melt away, the authors claim, and they add that the usual "low-fat, high-carbohydrate approach won't do it; it has just the opposite effect."
If you are very overweight, the initial phase of the diet (when carbohydrates are severely restricted) will almost certainly put you in a state of ketosis, which happens when fat breaks down to the point where excessive amounts of ketone bodies are produced and excreted in the urine. Ketones are incompletely burned fat, say the Eades, so that any ketones "you get rid of without actually using them for energy means you are ditching unwanted fat without having to actually burn it off."
Is ketosis dangerous, as many nutritional authorities say? Not at all, say the authors. Ketones are the natural by-product of fat breakdown, normal and important sources of energy. To facilitate getting rid of these ketones, they urge you to increase your fluid intake by as much as 50%, to at least 2 quarts of water-based fluids a day. High protein diets can be harmful, however, to those who have had previous kidney problems.
As for exercise, the authors favor resistance training, such as weight lifting, because it creates a neuroendocrine response, stimulating the release of growth hormone and testosterone more quickly than aerobic exercise. Why is this important? This is important because growth hormone shifts the metabolism to the preferential use of stored fat for energy.