Children beyond 1 year of age tend to have a decrease in appetite as they get to be more independent once they walk without support.Do not worry about milk intake (try changing the source of milk )Physiological anorexia is common in toddlers and they have strong taste preferences. Pediasure is a commercial product. There are no studies done on medical grounds on the product.
Next Steps
Try changing the milk source
Prefer fresh milk rather than packaged milk
Do not worry as it is expected in that age group
Health Tips
It’s growth and development that is important than just the physical parameters of weight of the child.
Consult your doctor for his global development assessment.