Therefore my advice is, to jump right into it. Eat what the locals eat. Do what the locals do. By this you have at least a bit fun until you have to spend your time sitting and sh*ing.
The human body is great in adapting to those situation. On my first visit to an development country I took more pictures from the window of my toilet than anything else. But since my body got somehow got used to the new environment, I have not been ill on my last few trips.
Final advice for third world travel: Have toilet paper ready. Always!