Most likely because you are not getting a very good workout. Post your workout.[/quote]
Give me a break! I have done workouts that strip my body of every last drop of glycogen, and I still get the post-post-workout meal slump if I eat anything more than a tiny snack.
Workout examples: 10,000 meter row in sub-38:30. 2 sets of 30 reps of 115-pound barbell clean and jerk in seven and eight minutes, respectively, with rest in between. 5 rounds of 21 reps of hang squat clean, run 400 meters in 17-something. 10 sets of 10 pull-ups and ring dips - ~60 minutes of exercise.
After these meals, I consumed a post-workout meal of ~800-1000 calories: ~400 cals protein, the rest high-GI CHO. ~30 mintues post-meal, I invariably experienced a huge bonk. I eat 3-4k a day.
Point: Even maximal glycogen depletion does not seem to me empty out glycogen reserves enough to eat more than a very small post-workout meal. And eating a very small post-workout meal kills recovery.