My son wont eat literally ANYTHING what do i do?

my son is 14 months and he is out of the stage of eating baby food ( gerber etc) he used to eat bananas and apples etc. now, he wont eat anything accept snacks.. i try to not give him snacks and put real food in front of him for about 40 min and he just wont eat. iv e tried string cheese, spaghetti, apples, zucchini, bananas, etc.. he just shakes his head no and wont eat but i do not want him to starve so i give him a chip, or a cookie its getting frustrating because i need him to be healthy and want that. he is loosing weight and that IS scary just like to any mother, if you have any suggestions on how to get healthy food into him please help.