Well, that's a big plus with Primal. If you are eating a good mixture of Primal foods they are so much more nutrient dense and filling/satisfying than what's recommended on the SAD. A lot of people making the switch report that they can get by on fewer calories and feel satiated versus before.
Don't be surprised of your intestinal issues get better after eating this way for a while as well. If you still want to do fasts then that's great (and I find them soooo much easier to do on Primal than what I was doing before) but you might find you don't *have* to in order to avoid embarrassment.
Keep at it and best of luck on your journey!