Question regarding elimination diet

[Catwmandu]

My son has been having very poor weight gain (see post http://mothering.com/discussions/sho....php?t=1180947 which should be read at your own risk for it's length),

My question is how severely an allergy could affect weight?

[Taryn237]

Stacy - You'll get some replies if you post this in the allergy forum. From my minimal research it can really affect weight gain...