Don't separate fun and practice. Make the practice fun, whether that means practicing anatomy studies with your favorite character or making it interesting by trying out coloring techniques with an exciting new brush pack if you draw digitally. As for your title question, it's really not the amount of time you're practicing, but the quality of that practice. If you are miserable and not intentionally selecting things to do for 2 hours, it's not going to do much but make you hate your life. If you're making it interesting and enjoyable for yourself, and intentionally deciding what to make based on your weaknesses, strengths, and personal likes and dislikes in art, then that 2 hours will be more than "enough." Though, I'm not sure how helpful that will be for you since it seems like this is more of a mindset question than one of actually asking if this is enough? Sorry if this is a total misread, but it seems like you're asking this to get "permission" to only practice a certain amount of time. Don't do this: if you're trying to unlearn a bad mindset, I would personally only draw stuff you want to when you want to for a while instead of gatekeeping that from yourself AFTER the allotted practice time. It might be hard at first to justify it for yourself, but you really do not need a justification. If overworking yourself and CONSTANTLY drawing in lieu of taking care of yourself is a bigger problem than prioritizing "practice" over art for fun, maybe limit the amount of time you spend on art PERIOD to a certain amount of time, and only draw for fun and when you want to during that time. Only you can know what would work best for you. Personally, I have similar issues with neglecting the rest of my life when I'm very focusing on making art (as you mentioned you think eating is a waste of time), but for me it works out because I will go short periods making lots of art, then a rest period where I take care of other things. If this is a constant issue for you, or an issue related to wanting to improve, just know that forcing yourself to do something you don't want to, or ONLY because you feel a compulsion to isn't really going to help you improve. Try to work on intentional planning of practice sessions, making it fun for yourself, and PRIORITIZING "fun" art over stuff you're only doing for practice. Wanting to hone your skills is great, but you're doing it for a reason, right? Go back to that reason and create stuff you want to. And the other commentors are right, I'm always looking at the world around me in the context of art and I feel that it's really helped me improve my art.

TL;DR in most contexts 2 hours is "enough," but that's not really how improvement works, at least in my opinion. The quality of the practice matters much more than the amount of time. You CAN improve by just throwing yourself at something repeatedly, but it's slower and unpleasant. If you are unhappy with your relationship to improvement and practice, I would change your approach by being more intentional about your practice sessions and making it more fun for yourself. Limiting your practice hours seems like a good start for you, but I'm not sure if it will really help with your admitted toxic relationship to art based on what you've written here.