This is a very interesting thread, if you ignore the people who have deviated from the OP's point.
Of course dress size is unreliable. Of course it is important that we are a healthy weight. Of course people shouldn't be in denial about what they weigh and what they eat.
However, some of the stealth point scoring on this thread is really spiteful. Really, is there any need to say it's "really easy" to stay slim when you have children? Obviously it isn't for everyone, or everyone would be. And all that stealth boasting about how dreadful people feel when they're a BMI 23 for example, that they can barely drag their great lardy arses down the street - it's completely unnecessary. Contribute something useful to the debate or just wander off into Evans and exclaim loudly in mock shock about how massive everything is.
So, what's resonated with me about this thread, as someone who is obese, is the UK culture of excess, coupled with the sense of entitlement when you're knackered/bored. Neither of those are excuses, and I need to be more responsible for my health.
I haven't lived in other countries, so I don't know much about the lifestyle, however the difference between the typical UK diet and a mediterranean one is marked, isn't it? There are far fewer sugar peaks, and food seems to be enjoyed, rather than craved and then regretted. The relationship with food seems to be much calmer, somehow.