yontel, I agree that being overweight is dangerous as well. However, the analogy isn’t perfect because it’s possible, and indeed, preferable, not to ever smoke, but everyone needs to eat. Therefore, it isn’t as easy to draw the line between eating and overeating (and this line can vary from person to person). Also, there’s no equivalent to secondhand smoke with respect to overeating.
That said, it is true that just as smoking causes/ exacerbates a host of other health problems, so does being overweight.
Also, it’s possible to experience health problems due to poor diet without being overweight, and obesity is not caused solely by overeating.