Here’s a Brazilian study that claims cesarean section isn’t a risk factor for obesity, which contradicts other studies that suggest an association between the two. Interesting finding, but this will need to be confirmed in other countries. There may be something about Brazil–cultural factors like diet, for example–that may overshadow cesarean birth’s alleged obesity risk.
Bottom line: obesity is a complex topic, and there are obviously many factors involved. Cesareans still seem likely to be a contributor, but to what degree remains to be seen.