This normally occurs only during starvation conditions, but also can be achieved by virtually eliminating carbohydrates. Ketosis can be an uncomfortable state, making many people feel sick and tired, not to mention giving them bad breath. Other problems arise as the body copes with a lot of protein. Stress on the kidney increases, with the possibility of kidney stones. With ketosis, a chemical called uric acid can build up in the blood, leading to gout, a painful condition of the toes and joints.
Osteoporosis is also a concern.
Not only is calcium low in the diet, but it is excreted from the body along with the excess protein. And the large amount of saturated fat in the diet raises the risk of heart disease. Numerous studies have borne out that the healthiest diet is high in whole grains, cereals, fruits and vegetables, with only a small amount of fat, especially minimizing the saturated fat found in meat and cheese. Such a diet, which is rich in vitamins, minerals and fiber, is associated with a reduced incidence of heart disease, diabetes, stroke and many cancers. I have seen people do this.