Read on Twitter
1) His white hair is due to a loss of pigmentation. That can be caused by extreme levels of stress which would quickly oxidize his hair, dropping the melatocytes levels. This can also happen IRL
2) His heart beats slower. This is called bradycardia. Is a condition where the heart beats under 60bpm. In his case, it was caused by intense exercise and training since he was a child. It& #39;s physiological, and prevents the heart from overbeating. IRL athletes also have this
3) While his heart may beat slower, it still works the way it should. During a fight, he still releases adrenaline, and cortisol. He& #39;s very capable of blushing, sweating, and having heated skin. If he didn& #39;t, he& #39;d be dead, mutations or not.
4) His mutations allow Geralt to over use/strain his body. This means, resisting the constant pump of adrenaline and cortisol needed to fight without having muscular or heart damage. This would also include a better sense of hearing and smell.
5)The potions do nothing more than to stimulate his own glands even more. That would mean even more adrenaline and cortisol.
6) His muscles, heart, and brain are probably really good at processing carbs and fats very fast. This means he& #39;d have to have a very fast metabolism, but also the ability to store proteins in the chance of starvation. Hence the bubble muscles
