Food is uncountable when it is used as a general idea in the context of the sentence. For example:
"We can't live without food."
However, if you are talking about food as a collective noun (aka a collection of different foods), then it can be considered as a countable noun, and therefore would need to have its corresponding verb conjugated to match the number of the noun. For example:
"The food from the restaurant was excellent."
"There were rows of food on the table last night."