This is a consequence that most people do not consider. Most people usually start gaining weight again. You will most likely go back to your old eating habits. You cannot remain on that type of diet forever, and sooner or later you will have to face real food again. They do not prepare you for this.
Most fad diets work.
The question is only how long can you maintain the results. Any successful weight loss will require a permanent change in eating habits. A good program should not only help you lose fat, it should also help you to develop the correct eating habits necessary to maintain your new body. Second You will lose more muscle mass than body fat. Muscle also gives you a shapely, firm and more defined physique.