Watch “Science of Fasting HD” on YouTube https://youtu.be/t1b08X-GvRs
Very interesting documentary. They research other mammals/animals to see how their animal body reacts to fasting and if any animals in the wild fast naturally.
They examined penguins, and the male penguins fast for over 40 days as they sit on the eggs of the female penguin to hatch. Over the course of the penguins 40 day fast, the penguin had 96% reduction in fat(lipid) cells and only 4% reduction in muscle mass. This is universal for all mammals/animals fasting with excess body fat.