I have a 13 year old daughter who has gained 20-30 pounds in two to three months. She has gone from size 8 to 16 in pants and there is absolutely nothing changed in her life in terms of exercise or diet. She isn t a perfect eater but does not indulge in junk foods regularly or excessively as she is a competitive swimmer. She swims 6 hours a week over a four day period and has had this exercise program for a long time. I got her blood tested and the doc said everything is normal but she is FULL of stretch marks everywhere and the poor girl is not loosing weight no matter what we try. It is very disheartening! We are trying a sleep test next to see if that might be a problem but truly I doubt it. My family has MEGA thyroid problems, mostly hypothyroid but I keep getting normal when the blood work comes back. Honestly I don t know what to do and being her age, it really is messing with her self-esteem! Any suggestions?