Watch this video, in which Paul Campos clears the air on the so-called "obesity epidemic." He says:
For most people who are classified as overweight, weight appears to have little or no independent health significance.
The correlations between increasing weight and health risk are weak, and usually disappear when variables other than weight are taken into account.
For example, the correlation between gender and health risk is much stronger: morbidly obese women have a longer life expectancy than ideal weight men. But there is no call for castration — which is well known to increase life expectancy — to solve the "testosterone epidemic".
Fat active people are just as healthy as thin active people, and are much, much healthier than thin sedentary people. Just one confounding variable — activity level — gets rid of almost all the correlation between weight and health.
Most people whom the government classifies as weighing too much are in the "overweight" category (BMI 25 to 29) and there is no basis in the medical literature for concluding that people in this weight range are at increased health risk.
We don't know if making fat people thin would improve their health.
There is no real evidence in the medical literature that significant long-term weight loss is beneficial to health.
The apparent health benefit seen in studies of weight loss is due to lifestyle changes, not weight loss.
We do know that encouraging people to lose weight does more harm than good.
We don't know how to make fat people thin in the long term.
Short-term weight loss followed by weight regain is bad for health, and this is the outcome of almost all attempts to achieve weight loss.
Therefore, it's irrational to form public health policy around trying to make fat people thin.