It sounds like it could be the beginning of an ED. As a person dealing w one I just can tell u: "Run as fast as u can..."(=see a counselor or T and talk about it).
The way u write about it makes me asking myself if ur thinking pattern is possibly more related to that u want to gain control over something, rather then to be an actual "weight-thing".
EDs can start for different reasons, one is as a coping process for the feeling of having too little control in some aspects of ur life.
So pls try to find a professional to talk about before this thoughts start to take total control of u.