Watery poo

Just browsed the delightul poo page http://chat.allotment-garden.org/index.php?topic=17568.0 over breakfast(!) and it says watery poo = too warm or not eating enough. 
We are fubenvetting but I don't have a run so she is free ranging as I can't bear to lock her in the shed for a week.

I know I'm probably undermining the benefit but could there be another reason to eat less?  I got a bit concerned when she didn't wolf down her favourite treats as she nornally does. Seems fine otherwise - moulting a bit and might be getting on a bit.