Why does no one respect me?

It means the people around you have made a solid opinion about yourself. They do not want to give any credit to you even if you have tried to overhaul yourself to look presentable. Please remember, do you think the change you have done on yourself either in weight loss or in your general behaviour pleases you, if it does then surely you should rest assure the change that has been wrought upon you will bring positive dividends. Keep trying. It should also be kept in mind that nobody learns through appreciation but through criticism. Always keep in mind that even the better of the best people are also denigrated by others. We are no exception. Pull yourself together and have positive bearings.