Losing weight has made me feel insecure.
Why has it made you feel insecure?
I see that I'm not appreciated by many people because of my appearance anymore.
Well, if losing weight makes you healthy, that's all that matters. You should feel confident in who you are. That will rub off on others and make them appreciate you.
I don't feel that healthy either. I felt better before I lost weight.
If you really feel this way, maybe you should consult a doctor about your ideal weight.  It's likely that you are in better health now than before, but that is a matter best left to a professional.