Hello, Welcome to Just Answer and thanks for your question. If someone is completely healthy otherwise and has only a few pounds to lose, it will not harm them to try this plan or any other high protein diet for 2-3 weeks if they can stand the monotony of it. For anyone with kidney problems, liver problems, heart disease, diabetes or hypoglycemia, etc. or more than 10 pounds to lose, it isn't recommended.
Any diet that causes someone to eat fewer calories than they expend in exercise and metabolism will result in weight loss. There is no magic about high protein versus a balanced diet, except that a balanced diet provides all the nutrients required by the body and will not harm anyone to follow. If someone follows a 1,200 to 1,500 calorie diet per day and gets some exercise (30-60 minutes per day is recommended for everyone), they will lose weight at a rate of 1-2 pounds per week which is a healthy amount to aim for. People should also carefully measure portions, since most of us eat 2-3 times as much as we think we do when we "eyeball" servings. Here are a few plans you can try to get you started.