More on obesity and lifespan
An amusing post from Different River about a study whose results show that among those who are overweight mortality is lowest among those who try to lose weight and fail. Trying to lose weight and suceeding or not even trying are associated with higher mortality.
Note that many of the confidence intervals overlap 1 and are therefore nonsignificant. I'd add to DR's explanations the possibility that some individuals who lost weight did so because of other health problems (e.g. cancer) which also increased mortality.
Most troubling to me was DR's suggesting this explanation:
Perhaps those who are losing weight on purpose are doing dangerous things to accomplish the loss. For example, not all diets are safe, even if they are successful. (Three doctors told me that if the only way I could lose weight was to use the Adkins diet, I was better off staying fat.) Also, some people may exercise beyond their body’s capabilities in an effort to lose weightAs an ultramarathoner who fasts one day a week to lose weight this hits a bit close to home