Religious orders all over the world do retreats and fasting and have practied these for ages. So, for your readers who were seeking more information on these, they can go and visit some of the convents. The priests and nuns would be able to share on these practices. Personally, fasting makes you free from your cravings and enables you to truly focus on what is of value. Retreat does the same. It make you let go of many attachments and distractions.