Just another vote for of course there is a difference! My weight has gone up an down a lot in my life, and the difference in treatment is astounding,
The first time it happened to me I was still a teen, I had gone on holidays with some friends, I was overweight and was treated appallingly by the boys there (we made fiends with the staff at the resort), they mocked me, teased me, ignored me, used me as the but of their jokes to impress my (slim) friends, the lot! They were really cruel, and I am embarrassed to say I did not speak up, in fact, I was nice to them, trying to ingratiate them so they would leave me alone.
The following year, we went back and I had lost a lot of weight, they were all over me then, and commented quite openly about the change, I must admit to being really quite awful to them, I was appalled by their behaviour and made it obvious, you know what? they still came after me! they did not care how badly I treated them, they still wanted to be my fiends, take me out, buy my drinks, they would chuckle when I was rude to them, and commented how cute that was, etc. I was revolted by the whole experience, but it taught me a lot!
So, no, it's not your attitude... or at least, it's not just your attitude!!