OK, this is admittedly a shameless plug for the academic institution where I work,

...BUT I know the instructor, a woman, who is quite good and has done a nice job making this course user-friendly, and it is a totally online certificate in exercise nutrition. It covers how food is fuel for athletic performance, determining energy requirements, gaining muscle, enhancing bone density and change body composition, environmental and genetic influences on health and weight management, yada, yada.

http://www.humboldt.edu/~extended/sp...enutrition.htm

Were I not supposed to be working on a Ph.D. dissertation I would take it, still might, anyway!