why was sugar rationed during ww2 and why was meat rationed?!

Sugar was imported--made in Hawaii and other places where sugar cane was grown--and very hard to get when trade was disrupted. Meat was at a premium, because most of it went to the soldiers on the front lines. So rationing was introduced in order to make sure that everyone could get at least a little of what was left, instead of the very lucky or wealthy getting all of it.

There were not the amounts required, and if you couldn't grow it yourself it needed to be imported.
Shipping food was a dangerous problem due to enemy actions, and a vast majority of the Merchant Navies was used to transport men and material to England.