It's a short term solution. It's simply an extreme form of calorie restriction, though I'll grant that the calories consumed are at least good calories.

The results of any crash diet are nearly always the same. You'll lose muscle and fat at about the same rate. When you go off the diet you'll have that much less muscle mass to burn calories. Expect to gain it all back and have it harder to lose the next time

Ask me how I know.

Fat runs rampant in my family. My sister and I have licked it after 30 years of working at it, and our answer has been lifestyle change. It works and it lasts. My sis lost 100 pounds 3 years ago and has kept off every ounce. I lost 40 and am very fit for an old guy.

Balanced diet, moderate calorie restriction, and exercise is the long term solution. if you want a plan that's proven to work, try "Body for Life".