maggie:

Oh, good lord.  If you're practicing every day and Crossfitting frequently, you're going to have to eat MUCH more glucose than you're getting from fruit and the occasional glass of milk.  With that much activity, you might even be short on total calories -- paleo foods are very satiating, and it's easy to not eat enough if you're very active. 

As I say in "Eat Like A Predator", "If you are active and not concerned with losing weight (or trying to gain it), you’ll want to eat more carbs than the average person trying to lose a few pounds."  Your parents (older, probably relatively sedentary, trying to lose weight) are NOT a good guide to what you (young, extremely active, probably still growing) need to eat.

I know that my athletic performance suffered for a couple months after going Paleo, because I didn't have a good feel for how much carbohydrate I needed to eat...I felt great mentally and for the first half-hour of exercise, but I bonked quickly because I was constantly glycogen-depleted.

How to fix this?  My advice: EAT MORE STARCH.  Not sugary fruit -- you don't want fructose, you want glucose.  Anything off the Jaminets' list of "safe starches" will do: sweet and regular potatoes (peeled), taro/sago/tapioca/cassava if you can get them, and white rice.

In order to keep your consumption under control (so you don't lose control and binge), eat the starch at meals (preferably dinner and lunch, not breakfast), and eat it last.  Eat meat and veggies until you're satiated with them, and then start on the potatoes or rice.  Baked and mashed potatoes, simple white rice with butter and salt, potatoes and rice in scrambles...

Rule of thumb: eat more starch until your athletic performance stops increasing.  If you start gaining weight or binging, eat less.  But since you're in strong physical shape, your body will probably tell you how much you need.

There are some advanced techniques you can get into later, but let's get the basics sorted first.

JS

(Annoying disclaimer: As always, this is simply my advice.  Your choice to take it, or not, is your own responsibility.)

Rob:

AFAIK the limit on anaerobic metabolism is generally the buildup of lactic acid, which drops the cell's internal pH far enough that the chemical reactions stop working.  This is because, under anaerobic conditions, the pyruvic acid produced by glycolysis is converted directly to lactic acid -- as opposed to aerobic conditions, where it can enter the mitochondria, be converted to acetyl CoA, and enter the Krebs cycle.

If you have sources which demonstrate otherwise, I'd love to see them!

JS

Mags:

It depends what you're doing!  For strength training of any kind, complete protein is most important.  In fact, I'm a big fan of protein after any workout: while muscles are indeed extra-sensitive to glucose immediately PWO, you can replete muscle glycogen anytime.  In contrast, your body has no way to store amino acids, so you'll need to provide them in order to allow protein synthesis that doesn't involve catabolizing existing tissue.  You shouldn't need a lot of fat PWO, since exercise frees it from your own adipose tissue.

In conclusion, something high in complete protein, with carbs according to how much intense glycogen-depleting effort you've put out.  Strength training doesn't use much: that's mostly dependent on the phosphocreatine system.  Intense anaerobic effort is what'll deplete glycogen quickly, e.g. metcons, HIIT.

Of course, real food is best, and you're not going to die if it takes you 30 minutes to get home and fix it.  But if you can't manage that, a can of tuna, some jerky, or a protein shake (and, optionally, a banana) will hold you until you can get to the real food.  In that case I use whey protein because it's absorbed very quickly.

JS