You do need more protein to avoid catabolism (breaking down of muscles for food) in endurance excercise, and to aid recovery, because some usage of proteins for energy is inevitable in endurance sports.<br /><br />This gives some info: http://www.nismat.org/nutricor/index.html<br /><br />Basically "The Zone" diet is marketing hype. The extra protein will be deaminized, the waste products ****** out, and the remaining carbos used as expensive fuel.<br /><br />This is a superb source of info: http://www.pponline.co.uk/encyc/nutrition.htm<br /><br />I do take protein shakes after exercise, but I do a LOT. Riding 15 miles to town, a 1 hour gym session, riding home, and then extra on the road training routines twice a week plus racing at weekends.<br /><br />Also, don't neglect micronutrients. I take multivits, zinc, cod liver oil, selenium, co-enzyme Q10, HMB (http://www.pponline.co.uk/encyc/0103.htm) and Glutamine.<br /><br />http://www.supplementwatch.com/ will tell you what is worth it and what is industry hype.