Food allergies can do this. Wheat does it to me. Milk protein might be your problem. This is easy to test, just replace your whey shakes with egg white powder instead and cut out all milk. If it solves your problem, try drinking a quart of skim milk and see if it brings your symptoms back. If so, milk allergy is probably your issue. It's quite common actually.
It actually did start happening soon after I started using whey and I also gave up on soy milk. I've always drank milk, but I'm consuming more if it here recently. I don't have to drink milk right before I feel like that though. I guess I'll cut it out for a week and see how it goes.
I do have some food allergies... like, I'm allergic to orange juice. I kind of found it out on my own. If I drink a big glass of OJ, I have an asthma attack 20-30 minutes later, very strange. I got diagnosed with all kinds of crazy mess trying to find that one out... I even got diagnosed with severe normal asthma and exercise induced asthma... got put on 3 different inhalers. Idiot doctors. I quit drinking OJ in large amounts and I was fine after that.
The other thing is it looks like you're inducing hypoglycemia.
Yeah I was worried about this because I am kind of hypoglycemic anyway. I have an appointment with an endocrinologist tomorrow afternoon so I'm going to have blood work done to test for this while I'm at it.
Also since we're on the subject... this will happen even on days off no matter what I eat. Today I didn't do a single thing that was even halfway related to exercise. I even had a big plate of whole wheat pasta for lunch at 1 PM, it had a little chicken, squash, zucchini, garlic, onion, green pepper, and mushroom tomato sauce mixed in but it was mostly a whole bunch of noodles. Same exact thing happened, by 4 PM I was so tired I had to take a nap for an hour and really didn't want to get up then.
Just seems like if it were a blood sugar problem with hypoglycemia and my blood sugar getting really low, then my training days would be worse than my off days, but it's not, I feel better when I'm exercising.
However, now that I think about it, I did have these same feelings right after eating yogurt for brunch. I woke up this morning and had eggs first thing, but then at 10 AM I minced up a fresh peach and mixed it with several spoon fulls of vanilla yogurt for some fresh peach yogurt. It was a rather large serving, half a bowl full. I immediately felt really sleepy, I mean, I didn't even get finished with the bowl. So... maybe the milk allergy thing is worth checking out, but, I've had it happen with other non-dairy things too, so I'm still confused.
Also your diet is low enough in calories and carbs for most people to lose weight without even exercising. It's borderline Atkins, which is ok, except you're starving yourself because of your training level.
Except I never mentioned the amounts of the food I'm eating. Trust me, I pig out on training days, and actually most any day at night. On hard workout days I'm eating close to 4,000 calories. Maybe that's still not enough, I dunno, but it's some hardcore grubbing. Or, maybe I'm not spacing them out good enough, getting too little in the morning and too much at night.
I'm not sure about the Atkins thing though, I'm regularly eating oatmeal, grits, fruit, grains, bread, pasta, potatoes, etc., some kind of carb source with every meal (5 or 6) on every day. Maybe I should bump this aspect up because of the workouts I do, but I've always thought that the amount of carbs I eat was well beyond any comparison to Atkins.