Robot it doesn't work like that I don't think.
If a person goes up to 16 stone. Then they consume 1800 calories a day and expend 1800 calories a day they will stay the same size.
If a person who is 10 stone consumes 1800 calories a day and expends 1800 calories they will also stay the same size.
I am sure that's how it is - the idea that larger people eat more than smaller people is not correct.
Garlicnutter this part of your post:
"Do you not find it odd that we - in the industrially-developed world, at least - are so obsessed by a wish to control our bodies? Can't we trust them to just get on with life? I'd hazard a guess that this is far more pronounced in women than in men - it's easy to observe men who don't betray any concern about how their bodies are functioning, but pretty hard to find a woman who isn't trying to rein in her natural functions and alter her physical configuration."
I really don't agree at all. Where businesses are trying to make as much money as possible and making foods that are intrinsically awful. And then market them very heavily from the cradle up.
For example drinks that contain artificial sweeteners. I was surprised the other day to realise that "no added sugar" squashes from "trustworthy" brands like robinsons contain sweeteners. I didn't realise (and I am generally quite careful about this stuff). Artificial sweeteners are a problem for a variety of reasons, and the labelling is misleading IMO in that when the average person reads a label that says "no added sugar" they do not think "oh that will have loads of nutrasweet" or whatever make it is. Ditto low fat yoghurts that are stuffed full of sugar instead, all sorts of foods that contain transfats etc etc.
These things are bad for you, the food is adulterated, it is not what our bodies need but it is cheap, available and it triggers happy sensations in the brain.
It has been left up to people's bodies to decide what they want, and in combination with a food industry aggressively marketing crap at us, we have a situation where people are becoming less and less healthy.
I think that is a social problem and should be addressed, but the governments will not take on the food industry - they are terribly powerful.
All that is on top of the feminist issues surrounding food, bodies, media messages and all the it which is an equally awful but gendered issue.