Cat locked in closet for 6 days

We just got back from being out of town and our one year-old cat was locked in the closet accidentally by our Pet Sitter for six days with no food and water. He ran out when we got home and opened the door and is acting totally fine now. He came out and ate some food, drank some water. We stopped him from eating a ton or drinking too much But he used the litter box, went to the bathroom, and is now playing with our other cat. He is acting totally fine and normal, running around purring wagging his tail, etc. Gums seem to be a normal color. He had pooped once in the closet. Do we need to be concerned and take him to the vet? I read about hepatic lipidosis so want to get him tested for anything if we need to Cat is fixed, no prior medical and no medication