High-protein diets are currently one of the most popular (as well as controversial) weight-loss techniques. Existing scientific evidence suggests that only one of the published studies examined the effects of high-protein diets on weight-loss and actually showed a decrease in body fat. It simply indicates that it is not essential that high protein diet will help in weight-loss. The weight loss by high protein diet may be due to water loss. Moreover high protein diet (in which more than 30% of required calories are coming from protein alone) can cause urinary calcium loss. This in turn can cause calcium deficiency in long-term and also predisposes individuals to kidney stones and other kidney problems.
Therefore it is advisable to avoid such diets (especially diabetics). The researchers concluded that following a high protein, low carbohydrate diet is not the best way to lose excess body fat and that more long-term studies are needed before these diets can be deemed safe.