The most basic principal to lose weight is to create an overall calorie deficit rather than varying the amount of protein, carbohydrate and fat in the diet.
Ideally by reducing caloric intake by 500 kcal/day one should lose ½ kg to 1kg weight each week. However, low-carbohydrate, high-protein diets typically produce weight loss of 2 to 3 kg in the first week and therefore seems fairly appealing to dieters. In reality this added weight loss is not due to any miracle but it is due to a diet-induced diuresis. Each gram of carbohydrate stored in the form of glycogen in the liver and muscles holds 2g of water.
The body has a total store of 500 g of glycogen (100 g from liver and 400g from muscle) therefore when carbohydrate is restricted, glycogen is metabolize with approximately 2 g for water (i.e. for 500g of glycogen metobolization 1 kg of water will be utilized) to provide energy for the body to work. In this process weight loss is achieved simultaneously due to the reduction of body total water content.
The second process that works in weight loss is ketosis. Ketosis occurs when your body does not get enough calories from carbohydrate and the body has to metabolize dietary and endogenous fat and thus resulting in weight loss. However this process of ketosis is an abnormal condition in which the brain is fueled by ketone bodies (by product of fat metabolism) instead of carbs resulting mental dilemma.
Despite of weight loss, there is several other detrimental effects associated with diets high in protein. Protein rich diets promote liberal intake of high fat meats and dairy products that raises blood cholesterol levels and in turn increases the risk of heart diseases.
High protein low carbohydrates diets also exclude fruits, vegetables and grains resulting not in deficiency of essential mineral and vitamins but also these diets will be deficient in fiber and antioxidants.
Thus the bottom line is that don’t get carried away by diet plans which seems quick but instead aim for a long term plan which is realistic and healthy.