[yummyfajitas]

The monetary cost of running is about $100/year, biking considerably less. As for the cost in time, the average person in the bottom 25% of earnings spends 30 minutes/day more watching TV than the average person in the top 25% (2 hours, 6 minutes total). (No breakdown for "poverty" vs "non-poverty" is given.)

I think the poor could manage some exercise or preparation of healthier food if they wanted to.

http://www.bls.gov/news.release/atus.t11.htm

[DrSprout]

Do you care for a family on your own? I'm talking about a specific class of people - primarily unwed single mothers - who do not have time for themselves. Their time is eaten up by making money for their families and caring for them.

Simply making the declarations that poor people don't want to work, and poor people are generally fat, even if true, ignore sizable quantities of people for whom exercise and healthy eating are not feasible.

[yummyfajitas]

You may be right about that narrow category. But there were only 4 million such women below the poverty level, circa 2007.