I have to ask first, is this a religious fast? If so, I admire you for it. I don't believe Gram was too harsh, hes telling the truth. Fasting activates a very primal survival trait our each one of our bodies has in it. Its called "starvation mode". The theort is back in the prehistoric ages, prehistoric man developed a mechanism to keep them alive during times with no food. The body would catabolize muscle in order to conserve energy. The body would also hang on to any bit of fat it could. Fasting can trigger this (only after 3-6 days) and start breaking down muscle. The reason fasting sounds so bad to people like Gram and myself (Im sure others would agree) is the thought of catabolizing the hard earned muscle we've built sounds sickening to us.
If its religious, then your religion is very important to you, good luck with it. If its an attempt to lose weight, please reconsider, there are better ways.
Thanks for reading this post.