[jamixoxo]

I have made some slightly depressing observations in my efforts to formulate this dietary bar...
...
So... My honest belief is that the reason we have so much obesity isn't actually because we WANT to eat too much. It's that we NEED to eat too much.

I'm not convinced there's a causal link to obesity... I did some poking around and this seemed to be the most relevant:
http://hortsci.ashspublications.org/cont.../1/15.full

I haven't fully parsed it, but the evidence cited suggest that it's dilution due to high yield rather soil depletion. This would be exacerbated in livestock, given the "higher yield" livestock consuming the "higher yield" feedstock.
I agree this would require an increase in consumption to avoid deficit, but I don't necessarily see obesity as the end result, and certainly not at the epidemic levels we have today. I thing the root causes are myriad - varying based on culture (I saw very few 'obese' and a reduction in overweight persons on a recent trip to the Netherlands, than compared to my workplace), income and other factors.
Income is probably the strongest argument for the causal link, where poor people are more likely to eat foods with low nutritional value, and also be obese.

While I think obesity is a bad thing, and the depletion of nutrients is also bad, I'm not pessimistic about a solution to either. We'll either figure out a way to a soft landing, or nature will do it for us. When I was in grade school, I remember predictions that "by 2015 we'll be drowning in our own:" and you just pick your poison... People, sewage, garbage, radioactive waste etc.. Since no one has come to put up a high rise in place of my house, I don't smell sewage, they take the garbage away every week at a reasonable price, and I'm not wearing a rad counter I'm not really afraid of 2015. Not because chicken little was wrong to warn, but because we did things, many, many things, that made sure it wouldn't happen that way.
What I think will kill us, in the long run, is apathy and indecision about these hazards.

-j