Yes, you can lose weight on many of the current diets. But, reduced calorie intake, in any form, can promote weight loss. Everybody needs protein, but more is not better. Excess gets stored as fat just like any other extra calorie. And that is hard on the arteries.
Osteoporosis is all ready a health problem for many.
Carbohydrates are your main source of fuel. When glycogen runs out, the body turns to protein, body fat and lean muscle tissue to supply energy. This process puts your body in ketosis, an unhealthy state often accompanied by nausea, headaches, fatigue and bad breath. It increases the acidity of the blood and can strain the kidneys. Ketosis does decrease appetite.