We are still as productive and alert, if not more, while fasting as we were before. I don’t know what sort of people you are surrounded with, but I personally do not know one muslim who is neglecting his responsibilities because of fasting.
Those who cry that 19-20 hours roza is too long, also say the same about 12 hour long rozay.
If you need tips on how to stay active and alert while fasting, please ask
