You're doing a parasite cleanse also? Then I agree.....fasting could be dangerous. Not only that, but you actually need food to keep the dead matter in your stomach moving.
But veg/fruit/nut fast would work extremely well in this situation, since you're not deprving yourself of anything. Plus the fiber will cleanse out your stomach.
If you're diabetic, I would recommend less fruits or any particularly sweet stuff. You can eat some, but I've heard of diabetics who eat entirely fruits (or high Sugar vegetables like carrots), and then end up having Sugar balance issues.
As for the amount to eat, here's the great thing: you can eat as much as you want. Even if you happened to be chewing some vegetable or fruit the whole day, your calorie intake would still not be enough to make you fat, unless you eat tons of nuts or vegetable fats like oil or avocado (a handful of nuts should be sufficient each day).
An easy way to remember is to eat as much water rich foods as possible, like celery, oranges, cucumbers, etc. and limit the intake of concentrated dense foods like bananas or dates, which are higher in calories. I don't recommend totally giving up on these denser foods, just don't make them your entire diet. People do it totally wrong and think they can lose weight eating dates all day. Each date is like 50 - 70 calories......that's like a cookie almost.
There are tons of resources you can look up for more information. thegardendiet.com is one example. Just type in 'raw diet' in a browser and tons of sites should pop up. I also recommend 'Fit for Life' a book by Harvey Diamond. Its mostly raw but they allow some proteins and carbs on their diet for people who can't live without it. The best is to leave them out. Harvey says he lost 50 lbs in one month. That just boggles my mind.