Fibre after fast: Sources? Timeframe?

I've mentioned my prior eating habits (rather bad), but one thing I often did right is breakfast. I'd take a quarter-cup of flaxseed and grind it in a coffee grinder, then drink it in a cup of orange juice, and chase with a cup of water (to make sure I had enough water, the flavor of flaxseed in OJ is actually excellent!). If I was feeling particularly, uh, studious?, I'd take a multivitamin too.

Now my question is: What kind of fibre is okay after a fast? Is pulpy juice good enough to clean me out? Does Watermelon have any fibre, or is it all absorbed by the gut? Tweet