NEWS YOU CAN USE: Intermittent fasting for fat loss or anti-aging?
[Those seeking to lose fat and build or retain muscle] use branched-chain amino acids (BCAAs), or leucine (one of the BCAAs) or perhaps whey (which is rich in BCAAs) during their fast. BCAAs are powerful signals that tell cells to ramp up muscle protein anabolism and to decrease muscle protein catabolism. So the use of BCAAs while fasting is the practice that will give one the best shot at retaining or even building muscle, even while doing regular, periodic IF.
However, one thing that BCAAs, whey, or leucine do is to stop autophagy, the cellular self-cleaning process. This process is radically enhanced by fasting, and it is responsible for the beneficial effects of calorie restriction and fasting. No autophagy, no anti-aging benefit from fasting.