Human societies are very complicated, dynamic, systems. It seems that when you fiddle with one part, other bits change in surprising ways. This new scientific research from the USA was interesting and surprising to me:
Smoking and obesity are the two leading causes of preventable deaths in the United States. Because smoking is subject to heavy government intervention, understanding the effect of smoking on obesity is important in determining the extent of unintended costs or benefits of such intervention…
We show that accounting for misreporting using the 2-step estimator developed by Nguimkeu et al. (2019) yields estimates consistent with the experimental literature; quitting smoking has a small positive effect on BMI. Our preferred estimate suggests reduced smoking accounts for 6% of the concurrent rise in obesity.
Does Quitting Smoking Increase Obesity? Evidence From Accounting for Misreporting