>>108522422Nobody suffering malnutrition believes that their diet is causing it, otherwise they would change their diet and fix it. If it's affected them since childhood then it's likely that in adulthood they imitate the kind of diet their parents fed them as a kid and just never considered there may be an issue there at all.
If you tell me a tiny shut-in Asian girl with jaw issues eats lots of vegetables then the obvious suspects are not enough complex carbs or red meat, protein, vitamin B, cholesterol, vitamin D, iron, zinc or collagen, or any number of enzyme disorders caused by too narrow of a diet. Many of these wouldn't show up on blood work intended to screen for genetic disorders or life-threatening issues. I wouldn't be surprised if she serially avoids foods that involve tough chewing and ends up with gaping holes in her diet that just don't register because eating rice and veggies every meal feels normal and healthy.
