Two days due to food poisoning (old wrinkly carrots just scraped instead of carefully peeled and eaten raw). For another four days I could just eat yogurth and strawberries with sugar and lemon, and always in small quantities at a time, as small intestine (not colon, as it happens most commonly) was bloated with bacterial gases and slowed down, so it could not accept more. Before I could eat at least a little, I even feared I should go to hospital, but luckily high-dose probiotics helped my immune system to react properly and heal.