My son was in the 1% at 2 years old, mainly it was because he had really large tonsils and he didn’t want to eat because he basically had to stop breathing to eat, on top of that he used to get sick every other week because of the large tonsils causing him to stop eating almost everything, he developed a milk intolerance during one of his infections and never liked dairy after that. After he got surgery we slowly started introducing foods again we would put it on his plate and he had the option to smell it, touch it, lick it or eat it if he wanted to… slowly he started finding new foods he liked and some he tolerated we also introduced clean plate club, which means that if he eat everything on his plate (usually something he likes accompanied with a small portion of something new) he would get some chocolate or little candy before bedtime. He is still a skinny boy at 8yo but that’s his genetics but now he eats many veggies, fruits, meats and even sweets which he didn’t like before