What are the best things to test over the two weeks?

Roughly your most normal diet, but also:

1. Individual snacks you’re curious about
2. Foods that you love but avoid because you think they’re bad for you
3. Foods you’ve been eating because you think they’re good for you, but you don’t really like them that much
4. Then try some variations on things if the spike you (eg switch raspberries for strawberries, or try a different brand, or try curry with rice instead of bread etc)