Baby is a very picky eater

[bright sparks]

A couple of suggestions...

I understand he doesn't like the pediasure, but it might be worth trying to make him some smoothies, you can pack all kinds of goodness into them and he wouldn't need to consume much to get some goodness into him. Green veggies, hemp seeds for protein and nut butters. Avocado makes any smoothie creamy like milkshake.

I'm curious...does he eat junk food? Like for example, if you bought him a happy meal would he eat it? I am wondering whether this is in fact a fussy eater or if there is another underlying issue. There are many conditions that result in loss of appetite. I know he has see the pediatrician but this seems a chronic problem if its in combination with being a small weight for his age. If he would eat the junk food but nothing else then I would say stand your ground and wait this phase out, he will eat eventually, but if this is not exclusively about certain foods, then I would fear that leaving him too long may result in further medical issues. Is everyone in your brothers life consistent with his eating? Is he on a rigid routine with meal times and naptimes? I ask because children thrive much better on a strict routine and this would likely help reinforce his eating habits if everything was always very predictable.

Is he taking milk? any kind, formula, 2%, homo?