Fine. "Yo-yo"
Now that we've clear this up, yoyo dieting is does not bode well for most people. People who lose weight only to gain it back often gain more then they lost. The end result being that they are fatter and probably less healthy then when they started out.
Some bodybuilders actually maintain a decent weight off season, rather than letting themselves go only to diet down for the next competition. Personally, staying within a lower variance of weight change is likely much healthier for folks in the long run. Also, not all large people are unhealthy, nor slim people healthy.