A recent blog written by Dr. Jason Fung, thefastingmethod.com; explains how and why fasting burns more fat while at the same time builds more lean muscle mass. Although human growth hormone reduces with age, fasting increases human growth hormone, naturally without supplements! Human growth hormone is one of the “counter-regulatory” hormones which rise as a result of fasting, this is how lean muscle builds, it is due to the human growth hormone which our bodies naturally produce in response to the fasted state. Great news, right?
Speaking of supplements, supplemented human growth hormone is associated with unwanted side effects like increased risk of prostate cancer and heart muscle enlargement, myocardial hypertrophy. Basically, if you workout, lift weights while in the fasted state, once you break your fast to eat, your body will build more muscle than if you workout while in a fed state. Also, while fasted your metabolic rate will not drop since an other counter-regulatory hormone, epinephrine (aka adrenaline) also increases while fasting. https://blog.thefastingmethod.com/fasting-and-growth-hormone/