Is this my fault? Should they be worried and annoyed?

Do my friends have a reason to be worried and annnoyed about me? I’ve been quite focused on getting my steps up and walking until i meet my goal, i’ve been reaching it every school day since Friday.

This being said I have been making sure to eat lunch and maybe one or two or three small snacks at school. A few of my friends have been telling me both joked. and honestly that they are concerned to me, i don’t think they should be though.

It’s my life, body and health, i’m not hurting anyone and yet they have been acting differently but won’t speak to me about it, i feel like they shouldn’t have a right to be concerned, i’m not doing anything wrong and i’ve explained that it isn’t personally and that if they need me or want to talk i am sometimes in the library after i’ve reached my step goal. I’ve also asked if they wanted to join but have multiple times said no.

So why are they concerned or annoyed by my actions, it’s none of their business what i am doing. Am I the one in the wrong and am to blind to see it?