Your male cat will be less likely to wander and get in to fights and therefore less likely to pick up infection and disease. A female neutered cat will be in better condition with no hungry litters to feed, and less likely to contract certain diseases. Neutered cats get fat. Your cat will only put on weight if you over feed it. A neutered cat will stay trim with a normal, balanced diet.
Cats are perhaps the most curious creatures on earth.
They can get themselves into a whole lot of trouble because of their curious nature. The cat is an explorer and is constantly on the hunt. Part of the reason for their curiosity is that they are always looking for food. Some hunts don' t end up all that successful. It is probably a happy dream about chasing and catching mice.