I have done many fasts with Liver Flush before the fast and many fasts with Liver Flush after the fast.
All cleanses before the fast are helpful simply because your body is cleaner before the fast than it would have been without the cleanses. Liver is a cleaning and manufacturing plant of our body. If it is clean your body will do better with the fast.
Fasting is amazing and has its benefits. Ultimately, we are sick or healthy because of what we eat, what we think and the environment we live in.