Body permanently altered

Hi, I have a story of overeating, undereating, overexercising, insomnia, general anxiety. So I have this set of beliefs around me having messed up with my body in a way that has caused permanent alterations to his functions. The “evidence” is all things of my body that are not functional as before I started worrying about my weight. With respect to say 10 years ago:
– I am no more able to have full nights of sleep
– My body is much more sensible to bloating fibers, gets easily constipated, which I did not have before
– I have fat on my abdomen that now is much more sensitive to what I eat, and saggy skin that I did not have before that just seem to expand
– I am less resilient to physical and mental stress
==> Again my brain uses all of these observations to believe that my history and all of my behaviors have led to permanent alterations of how my body works, which feels very similar to “I am broken, and I caused it”
Feelings are dejection and regret
I am not taking active actions from these feelings, rather inactions, but I am wondering how these beliefs & feelings are preventing me from discovering that my sleep and my metabolism aren’t permanently damaged, but might be capable of full recovery. How would you suggest me to coach myself to find out if this is the case? I find this last thought to give me hope but at the same time, I have the fear it is just me going to fantasy land and creating illusions. How do I distinguish creating new beliefs from going to fantasy land? Thanks a lot