Fasting and building muscle!

I've read the obesity code and the ultimate guide to fasting. I know as long as you lift heavy 3 days per week while fasting you won't lose muscle mass. My question is can you gain muscle while doing a long fast. If you continue to lift weights, can body fat stores aid in muscle GROWTH. I've expereminted a little on myself PRing a deadlift after a 48 hour fast. So I'm curious on the science of this, if anyone actually knows I'd greatly appreciate a scientific answer on this questions. Thanks in advance!

Answer

I actually wrote DR Fung and he responded, any one who is interested. Please see his answer below.

You build muscle upon refeeding. If muscle is your goal - usually would stick to shorter fasts (24 hrs)

On Fri, Mar 17, 2017 at 8:53 PM, Dr. Jason Fung <contact@intensivedietarymanagement.com> wrote:From: James Murphy Subject: Fasting Question Message Body: Hello Dr Fung, I’m a huge fan of the Obesity Code and the Ultimate Guide to Fasting. I suggest them to everyone I know who asks for my advice on weight loss. I was curious I know fasting won’t cause muscle loss, however during an extended day fast from 3-7 days, are you able to build new muscle?

Answer

You don’t need to lift weights to maintain muscle mass during a fast. As your body burns fat stores while fasting, It converts that energy into muscle which is sometimes why you don’t see as much loss over long term fasts.

https://intensivedietarymanagement.com/fasting-and-muscle-mass-fasting-part-14/