Is it normal to feel zero hunger all day but be starving at meal time?

I’ve noticed something weird with my hunger lately and I’m wondering if anyone else experiences this.

During the day, while I’m doing my normal activities (school, walking, etc.), I feel absolutely no hunger at all. In fact, thinking about food sometimes even makes me feel kind of grossed out.

But when my usual meal time comes around (I have a pretty fixed schedule), it’s like a switch flips. Suddenly I’m extremely hungry and feel like I could eat everything in sight.

It’s not like I’m forcing myself to eat earlier either — I genuinely don’t feel hungry until that moment.

Has anyone else experienced something like this? Is it normal for hunger to basically “turn on” only at meal times?

(Btw I just started keto, is it normal that my pee smells kinda like like cheap plastic and my breath like weird??)