If more countries treated obesity as the disease it is, we might learn the real causes, and maybe have some effective treatments. All the noninvasive treatments don’t work long term for the vast majority from what I have read.
On the less proven track, there are hypotheses that obesity may be driven by bacteria that colinize the gut and impact brain function to train a person to be addicted to certain foods. Still far from proven, but if the funding was there we might know one way or the other.