No way hosay Lets say a student eats in class time and a bit spills. No probs right the cleaner will clean it. WRONG cleaners are not our personal slaves, they are only here to clean floors and toilets.
Also (as others have said) it is very disrespectful to a teacher to eat while he/she is trying to do their job. If a teacher is speaking put everything down and LISTEN.
Some people may say that it helps their energy levels. But it actually sometimes gets your energy too high and you wont be able to stay still for even 1 minute let alone learn anything.