All your responses are interesting and pretty refreshing to read.
My own perspective comes from the research I'm doing for my PhD. I work with children aged 7 to 11 and look at factors contributing to the eating and exercise habits they adopt, the body size they prefer for themselves and their perceptions of societal norms and preferences of body shape and size.
All this can help inform our understanding of restricting eating disorders and morbid obesity, to name just the dichotomous ends of the spectrum.
It seems that children rapidly learn to override biological cues of hunger and satiety, leading to cognitive control of food amount, food type and frequency of intake. Mostly this seems to be influenced by familial eating patterns and food buying habits. Some children learn to eat far more than they need, some to obsessively restrict their intake of 'bad' food (oh how I HATE the moralisation of food - sinful, bad, naughty etc.), some to use food as a way to manipulate their parents or find emotional satisfaction.
So how does this relate to the current issue? Well, what I notice is that a lot of children are just plain unhappy around food. By the age of 11 a sizeable minority also articulate an idea of eating / exercise being transactional activities where one can be used to compensate for another.
What should we be aiming for then, if not slimness as an ideal? Ideally we need to get better at listening to our internal hunger cues and relinquishing the cognitive control of hunger in favour of what our bodies are telling us we need. We need to step away from the punitive aspects of health promotion around body mass i.e. concentrate on helping people get to their own comfortable, fit set-point in weight and never mind the BMI charts.
If an emphasis on exercise can achieve this, all well and good. But still I worry that until we stop living in such an obesogenic environment - where crisps and chocolate are on 'three for two' but never apples, where fattening foods are imbued with mystical characteristics such as 'tempting' and 'wicked' and where children are generally born to parents who themselves have a less-than-easy relationship with food, we won't really get anywhere. We have to change the way we relate to and market food, rather than ignoring it in favour of exercise. We concurrently need to make moderate exercise as accessible and socially desirable as possible, of that I have no doubt, but our efforts in this sphere absolutely have to be two-tier because right now, as a nation and beyond, we have such a messed up relationship with food.