thin

Fit indicates effort. More precisely, it indicates effort and reward. This is a good thing to teach ourselves. It is different to the effort/reward cycle for thin as that often involves unhealthy habits and mainly consists of deprivation.
Recently I walked into my local swimming pool at 6.30am. Among the swimmers wiping sleep from their eyes, there was one woman racing up, down, up, down, up, barely raising her head for breath. What assumptions are you already making about her? Keen? yes. Fit? clearly. Thin? no.
The newish minister for public health probably thought she was being sympathetic with her comments about obesity and the poor. But she was really just revealing her prejudices.
Our main objective then as individuals should be to stay the heck out of hospitals! We also should be helping others to do the same by living healthily. Obesity is a choice, granted it may be an economically influenced one in some cases (people who eat junk tend to be less educated than those who do not) but by putting a fast food shop in walking distance of every school are we really being smart?