Effects of Oral Nutrition Supplements in Children With Disease Associated Underweight

Inclusion Criteria: 1. Children treated at the participating paediatric centres during the study period (inpatients or outpatients) 2. Age between 24 months to 12 years at inclusion 3. WFH at inclusion \<- 1,5 SD - \>-2,5 SD (based on WHO) OR Decrease in WFH z-score of ≥1 SD within the last 3 months, and underlying disease with high risk of undernutrition 4. Children who would be considered candidates for oral nutrition intervention (but do not need tube feeding) 5. Written informed consent of parents/caregivers Exclusion Criteria: 1. Children in need of intensive care 2. Inability to consume ONS (e.g. major gastrointestinal dysfunction) 3. Children, for whom normal nutrition intervention would be inappropriate (e.g. food intolerance, allergy) 4. Use of parenteral feeding and/or enteral tube-feeding 5. Severe edema (\>0.5 cm pitting edema on the dorsum of the foot) 6. Participation in another intervention study involving investigational or marketed products concomitantly or within two weeks prior to entry into the trial. 7. Children having received enteral nutrition treatment for underweight in the previous month 8. Oncology patients during chemo-, radio-therapy 9. Expected hospital stay at inclusion longer than 7 days \-