@Sk2345
It can be. Lots of people with depression experience low self-esteem. This can manifest as insecurity and/or agression.
Insecurity alone isn't an indicator for depression or for mental illness necessarily.
If you think you or a loved one might be suffering (from a mental illness or other outside influences) then getting professional help is always best. If that's not an option, check out the therapists here on 7Cups or talk to a trained listener.
Personally I believe it can be a part of depression. I have struggle with my appearance for a long time. I'm not where I would like to be health and weight wise and that upsets me which then makes my depression worse. I am trying to not be so hard on myself and just take it one step at a time. Please try no to be so hard on yourself and let your insecurities get the best of you. I know that's easier said than done. But just know you aren't alone.