I followed a diet like that (but with more vegetables) for a couple of months a few years ago. It was the McDougall diet - very low-fat vegan. For the first week I felt great. I had more energy and my post-nasal drip and eczema started clearing up. Then I started realizing I was constantly hungry. I was eating every hour or two. I had constant stomach aches and terrible gas. I was always cold and rather miserable and starting going to bed at 9pm, just because I was so cold and hungry. I was eating a TON of food, but it just wasn't satisfying. Then one night I found myself craving mayonnaise in the middle of the night. LOL. I got up, ate a mayo sandwich (no kidding) and went back to bed satisfied for the first time in weeks!

I lost eleven pounds but it was NOT worth it.