Is it normal that my friend hates my advise?

That's his choice. Would be worse if he was like a friend I had who was like that yet constantly complained about his weight but wouldn't stop eating junk and drinking alcohol.
These types of people know what they're doing though, not to mention food can be an addiction like anything else but the person has to want to change themselves. Few people appreciate you commenting on their weight as it is a very insensitive thing to do. Try to get your friend to come with you to the gym or something instead but if he refuses to do anything to get into shape then there isn't much more you can do.

He sounds like a toxic blob.

It’s good you care enough to voice your concerns and try to help him but if he’s gonna choose to keep going forward that way after voicing those concerns and you backing down from enabling him further - unfortunately that’s on him.
It’s never exactly thrilling to watch someone bury themselves in their own grave persay - but you can’t force someone to change their mind about things they’re dead set on, they have to figure it out for themselves. If it means you being attached in a caring since enough, you may have to detach yourself some if it’s conflicting you to the point you’re worrying or anything like that.

I have a friend who is the same way, but not obese (though he is pre-diabetic). He is an insanely picky eater and refuses to eat anything but processed food. No fruits or vegetables, most meat has to be fried, and his diet mainly consists of chips, candy, fast food, TV dinners, pasta, and pizza. He also drinks soda and sugary drinks like they're going out of style. I've told him he needs to watch it, but at the end of the day, only he can control what he eats and allows to affect his health.

The only thing you can do on your part is to not buy him the food. Other than that, it's a choice he's going to have to make, unfortunately.

I'd be annoyed too if I had someone nagging me about what I eat.

I had a friend who had a go at me for trying to teach them that their actions were needlessly harmful to another. She had broken up with a good guy who just wanted more emotional support than she was capable of giving. Rather than hear me out, she felt I was just making her feel guilty and that "true friends don't teach eachother lessons". At the end of the day it was their choice. In my case I ended the friendship because I couldn't stand by that person anymore. In your case I'd suggest either respecting their decision and no longer vocalising your feelings on the matter as they clearly understand what they're doing and don't care. Or you can back away from the friendship if you're unable to see what they're doing to themself

Its good you care about their health, but its up to them if they actually want to do something about it. If they're not interested you wont get far and you should stop bothering them with it. Its either way their life and their body, and they are (I assume) and adult that can take care of themself. But you are fully justified to refuse to buy them junk-food, that is something that they ask from you.

If he wants to be a fatty that's his choice. All you can really control is you.

Dont buy him junk food. Dont contribute to the problem.