Not fauna, because apparently the denizens of our guts are - as bacteria - lumped in with the plants.
I have today what is euphemistically termed a 'stomach upset'. It's left me tired and rather sick .. I'm blaming exposure to dodgy members of the public at IKEA yesterday, where we bought frames for our Musee d'Orsay prints. (Update: I think it's the norovirus bug).
A small footnote on the zero-carb concept (protein and fat only, as in the 'paleo-diet'). This can starve our trillions of gut-symbiotes, good as well as bad, so is not too cute a strategy. Intermittent fasting is consistent with 500 calories of carbohydrates on the 'non-eating' day.