Why did the U. S. government use rationing for some foods and consumer goods during World War II?

I have not technically learned about WWII yet, but I can infer that they had to ration foods as the countries they were in war with (and their own country) had to send their men to war, so no one was working on the farms. Resulting in a lack of food and goods.

the french attack on germany was caused by the military alliance