In my opinion based on what i have read, in terms of breaking a fast, the digestive simplicity of the food is much more important than the number of calories. I would feel fine with 1000 calories from fresh juice long before i would feel fine with 300 calories from raw nuts which are perhaps 10-20x more digestively challenging than fresh juice. I doubt i would have 1000 calories of juice the first day after 20 days of water only, but depending upon how i feel and how much appetite i have, perhaps in the neighborhood of 500 the first day and 1000 the 2nd. But with a 20 day fast i would have nothing but juice (and some veg. broth) for 5 days after the break (1 day for every 4).
"Sorry if this post is extremely stupid, but it's just on my mind."