What is the recommended protein intake?

Many thanks for your positive comments, that's very nice to hear. Lots of questions so I'm going to go with succinct answers...

Let me answer the last question first. Because you are presumably on a high-carb, high-calorie diet to best fuel your training endeavours), your protein intake of 2g per kg is probably just about right.

Outside of poor-quality protein sources or those primarily from plant sources which aren't fully digested and absorbed (due to fibre binding, etc), the human body "absorbs" almost 100% of the protein you eat. So very little protein is eliminated in the stool/faeces. "Absorption" is the movement of the protein, as amino acids and peptides, from the gut into the bloodstream.

When most people ask this question though, they really want to know how much protein is "retained" in the muscle (which is NOT "absorption"). This question could take a great deal of time to answer properly but basically this depends upon: 1) bodyweight 2) training duration 3) training frequency 4) type of training (weights vs aerobic, etc) 5) training intensity 6) genetics 7) hormone profile 8) calorie intake.

Supplements that improve/alter hormones like insulin, testosterone, IGF-1, GH, etc will influence how much protein is retained by the muscle (cinnamon increases insulin efficiency).

The best research says you need about 1.6 grams per kilo of protein but there are several indications that increasing that slightly to 2g/kg makes sense so as to err on the side of caution and to obtain the other advantages of a higher protein diet such as general health, bone strength, lower bodyfat and higher lean mass. Also, if you decrease your calories and want to retain maximum muscle, protein intake should be even higher than this.

Oh ya, another thing, whenever people talk about protein, they always seem to want to recommend the minimum amount that one can "get away with". They never talk about the "optimum" amount. For example, the 1.6 grams per kilo recommendation for athletes comes from research that looked at the minimum amount of protein required to allow positive nitrogen balance (more amino acids going into the muscle than coming out). This does not inform us as to the optimum amount for body composition, performance, hunger (protein decreases appetite), thermogenesis (protein increases the rate at which we burn calories significantly more than carbs or fat), etc.

This is why you often hear different protein recommendations being advised from mainstream dieticians versus sports/bodybuilding nutritionist - the later are considering the "big picture" effects of protein intake beyond just meeting minimum needs for bodily maintenance!