WHY GO ON VEGETARIAN FAST DURING 9 EMPEROR GODS FESTIVAL

My vegetarian fast for this year has just started at midnight. During the 9-Emperor God Festival, one is given the option of going vegetarian for 1, 3, 6 and 9 days. Those who fast for 9 days usually add an extra day, i.e., on the eve before the start of the festival.
Going on a vegetarian fast does not only mean just eating vegetables, aphrodisiacs and not taking any meat. It also involves minding our thoughts and actions as well. We are also encouraged to do more good deeds during this time.

REASON FOR THE VEGETARIAN DIET
Actually, the main reason why devotees of the Nine Emperor Gods go on the vegetarian diet during this festival is to cultivate their minds and souls. There are some worshippers who do not really get the fundamentals right and end up making lavish offerings to the deities and do so with the aim of seeking personal gain. Do they think that these deities really need the mountain load of items offered? Also do they think that by offering such 'bribes' to the deities that they will get fame and fortune in return? From what I have learnt, it does not work that way.