Macronutrient Needs

source: http://forum.bodybuilding.com/showthread.php?t=121703921

Protein

The general sports nutrition guideline based on most studies out suggest that in the face of adequate calories and carbs then the following protein intakes are sufficient:
STRENGTH training -> 1.2 to 1.6g per KG bodyweight (about .6 / pound)
ENDURANCE training -> 1.4 to 1.8g per KG bodyweight (about .8 / pound)
ADOLESCENT in training -> 1.8 to 2.2g per KG bodyweight (about 1g / pound)

Eventually I want to get into a well rounded training of cardio and strength exercises, so I'm going to go with 1.5g per kg bodyweight.
1.5g x 68kg = 102g of protein per day

Fats

Generally speaking, although the body can get away with short periods of very low fat, in the long run your body NEEDS fat to maintain general health, satiety, and sanity. General guides:
Average or lean: 1 - 2g fat/ kg body weight [between 0.45 - 1g total weight/ pounds]
High bodyfat: 1-2g fat/ LEAN weight [between 0.45 - 1g LEAN weight/ pounds]
IF low calorie dieting - you can decrease further, but as a minimum, it is not suggested to have LESS than about 0.35g/ pound.

I'm pretty average for bodyfat, but I don't want to live like I'm dieting non-stop or I'll go mad. 2g per kg for me!
2g x 68kg = 136g of fat per day

Carbs
Since I'm not an athlete, I will calculate my carbs from the calories left over from fats/ protein:
carb calories = Total calorie needs - ([protein grams as above x 4] + [fat grams as above x 9])
carbs in grams = above total/ 4

So for me, the formula is:
2100 - [(102 x 4) + (136 x 9)] = 468
468/4 = 117g of carbs per day

To summarize, my daily macronutrient intake should be:

102g of protein per day
136g of fat per day
117g of carbs per day