Hair loss is a common thing between everyone and at every age the reason is diffrent .If you are between the age of 14-18 then the reason for your hairfall is very limited the most possible reasons are you might not have a healthy diet which leads to deficiancy of vitamins (b12, vD). Now to stop the hairfall and increase the hair growth you can add following things in your diet .Almonds, cashews,walnut,raisns,nuts,these nuts and other dryfruits whichever you like.Then you have to increase the intake of green vegetables like spinach,kale,spring onions,cabbage these will not only help in hair growth but they also provide other essential nutrients.It does not end here you should also increase the intake of beans like pea beans, sprouts,soyabean,legumes.You should also increase your intake of meat .And the most exciting part eating dark choclate also increases hairgrowth.If you are having a serious problem of hair growth you should consult a doctor immediatly.