Not that you should yo-yo, but it seems if you do, don't give up, cause it's OK to try again. Study participants were all older females, but as the article says:

It's not clear whether these findings would apply to, say, men, or younger women. But, McTiernan advises, it's certainly worth a shot.

http://todayhealth.today.msnbc.msn.com/_news/2012/08/16/13317870-actually-yo-yo-diets-dont-screw-up-your-metabolism?lite

BTW, I put this under Losing Weight, but it's also about Gaining Weight. There doesn't seem to be a General Nutrition category, or Healthy Eating, or some others that might work for this general topic of nutrition.