I'm not sure what the guidelines for an actual high-fiber diet plan are, but I know that I try to get a good amount of fiber in my main meals. Fiber is great because it can really fill you up and, for me, makes me feel less hungry between meals. If I have a high-fiber breakfast, I'm usually not hungry until lunch time.
So it's worth adding a good amount of fiber to your diet to aid your weight loss. Plus it's great at lowering cholesterol and regulating your insides!
The only advice I have is if you're going to go high-fiber as your main plan, do it gradually. I made the mistake of adding too much fiber too fast and man, it was unpleasant. Felt bloaty and gassy and miserable.