Having briefly wandered around the halls of Professional Public Health (Psychology) I'd be a bit careful about tossing the baby out with the bathwater. The research on childhood obesity doesn't rest solely on spurious grounds. I suspect most professionals would be cautious about the application of a height/weight chart to a child or teenager - there are such huge differences in development.

What I find scary about the obesity debate is that it is much worse to be the right weight and unfit than to be obese and fit (though the two often go together). We should really be more worried about the "unfitness epidemic", but then fat is Teh Evol in todays society.