OKwell here's the deal, im 14 and ive always wanted to become a vegetarina (b/c of ALL the reasons, mainly the killing animals thing, being healthier, i don't really like meat) but my parents were worried about my health and didnt think i could do it b/c i hav sum wierd medical issues already but i FINALLY convinced them last summer and wut i did was start it off slow, think of it as quitting smoking cold turkey- it can be harmful to you- so i needed my body to adjust to the change so i choose just chicken to eat for like a month then i went full veggie but just choose 1 or 2 meats to eat occasionally for a month (if u pick 2 then go the next month with 1 and then go full veggie the next month). it helps ur body adjust to the decrease in protein, iron, etc. but if ur child decides, a portion of vegetarians don't consider fish meat, so if they want, they can choose to still eat seafood (lol i don't though) but they hav to eat ALOT of high protein and iron foods like avacados, seafood (if they choose), beans, nuts (i hav pb and j everyday + more protein and i still hav a protein deficiency!) u hav to be extremely careful though, i hav terribly bad dizzy, lightheadedness spells, im constantly freezing, get headaches, and bone weakness b/c i still need more protein so i hav to go get supplements and get a blood test and stuff. a good thing to do is take ur kid to a nutritionist, and SUPPORT THEIR DECISION!!!!! i cant stress that enough, its really depressing wen family members arent carzy about ur decision and supportive, (it worsens things) othrs don't hav to like it, its the persons chioce! but like ppl saying "o i could nevr liv w/o meat i don't know how u do it!!!" its fine, it makes us veggies feel special, lol! it sounds stupid but its really good encouragment if they hav a 'vegetarian keepsake' like i hav a shirt that has a brontosaurus (plant eater) that says vegetarian, its really cute! and my cousin has a shirt with a carrot smiling saying "vegetarians have more fun" it makes us able to express our uniqueness n wen ppl look at the shirt and say "really, ur a vegetarian?!?, good for you!" it keeps us going strong, but its also a healthy choice as long as you find supplements for the lost nutrients, your doc. can advise a certain vitamin if they hav any good ideas! TALK WITH YOUR DOVTER, make sure they know!
Good luck to my future fellow vegetarian!!! i support you fully!!! (PS, if u like go to partys though and u don't know wut their serving don't forget to bring a few small snacks to hold u off just incase)