Not sure what your purpose in fasting is, but if it is to lose body fat & therefore detox and if you don't want to lose muscle mass, make it a protein-modified fast by adding in some lean meat. Gentle walking for 20-30 min daily.
The question I have is why just a bone broth fast?. My current protocol is itermitant fasting: bulletproof type coffe, (my own version with added 100% bakers chocolate melted and mixed in with cocnut oil and butter), 2 cups of bone broth around 1:00, followed by my first meal around 2:00 and then dinner around 6:00 and maybe a banana at 8:00. I have been doing this for a week with decent results. I've been LC paleo for over a year and stalled, this seems to be moving things along so far.
Adding carbs isn't likely to help. The point of a fast is that your body has to use what it has stored. If you give it too much support it gets confused and instead relies on you to feed it. I don't know how I'd do on a broth fast, it's easier just with water, but I'd suggest concentrating your broth into one meal a day and stick to non-caloric drinks the rest of the time and let your digestive system rest. Once you get used to it it'll stop pestering you so much.