I tried it when I was in college. I really think it's too restrictive and unbalanced. Yes, you may lose some weight, but the acual health benefits of eating half a grapefruit with every meal are minimal, and you'll sure get sick of it quickly! I also ended up eating a diet very high in saturated fats, which sure can't be helpful!
Unfortunately, a lot of doctors really don't know much about dieting and weight loss unless it is their specific area of expertise. I'd much rather hear a doctor suggesting a diet based on whole foods, or a plan such as calorie counting or Weight Watchers (which is basically calorie counting with a little variance based on fat and fiber). I also think South Beach is a fabulous plan, as it teaches you to eat "good" carbs, not just eliminate them completely.
Highest known weight: 324
Weight on morning of DS surgery: 308.5
Got down to about 185 before pregnancy;
Benjamin David born March 24, 2012, 7 pounds 11 ounces