Hi Gemma. The following is my personal opinion (formed from my own experiences and observations), so don't take it as gospel - rather, something to take onboard and consider:
First, don't fall into the mistake of assuming most people are obsessed with how other people look.
It's natural for each of us to think we're at the centre of everyone's attention. And that may be true for a few fleeting seconds when we catch their eye. But most people are self-centred and are predominantly thinking about themselves: "how do I look", "what is he/she thinking of me", "I'm thirsty/bored/tired", "I do/don't feel in control of my present situation", "do my clothes look good on me?", etc.
Even when people DO pay attention to someone else it's often just to compare so they can boost their own self-esteem. It's nothing personal, and the aim of the comparison is to boost their own ego (yet more self-centeredness!).
However, there is one solution:
The solution is not some magical fairy dust that, when sprinkled over other people, makes them non-judgmental and accepting of everyone who seems different. That's never going to happen since human nature cannot be changed even with fairy dust - or anti-discrimination laws, for that matter. The only solution is to lose weight and become fit and healthy. It will take time. It will be difficult. It will be one of the best things you'll ever do in your life.
As you lose weight the first ten or twenty kilo loss will be noticeable to people who see you regularly. And you'll feel better and more confident as you address the internal issues which caused your weight-gain in the first place. Eventually people won't take any more notice of you than they do anyone else. It will take time, but as long as you have a good plan, determination and are honest with yourself then it will happen.