Why am i not thinning out?

im 16, should of had a growth spurt of some sorts, but no not me. i exercise adjectives the time... i do INTENSE swimming for at least 2 hrs and some times up to 3.5 hrs around 6-7 times a week. i do some crunches lunges and running... yet i still see other girls who don't even workout at adjectives that are still thinner then me. what is up next to that? i eat in good health and take my vitamins. plus my parents be very fit at my age... mom run track and dad did soccer/rugby... what the heck? im not thinning out grrrrr Go the the doctor and see what he says. are you within your normal counterbalance range? If not consequently it may be possible you have a thyroid problem especially if your parents be fit at your age. Metabolism is partly genetic.
I own to say though Kudos to you for exercising and staying forceful.
maybe your already as tough as is healthy for your body?