After much marathon and trying off to shed some fats/water, I didn't lose any weight.
Now that I try to offload another 300 ml of blood away from my body, I hope I would have lost more water and fats in my body. :D
Nah.. it's a myth. we can't lose any weight by donating blood.
It's my 13th time doing this since 2000, yet I dont see any reduction in weight by doing so :P