The proposed study is a double blind, randomized, placebo controlled study. The aim of the study is to evaluate the effect of nutritional formula supplementation on growth of prepubertal children treated with stimulants medications of ADHD.

70 Participants treated with stimulants medications of ADHD will be randomly assigned either to the intervention group or the placebo control group. Randomization for the two study groups will be made in a ratio of 1:1. Both participants and study team will be blinded to the type of treatment that each patient will receive during the study. Randomization will be stratified according to gender.

Participants in the intervention groups will be treated with the study formula and participants in the control group will be treated with a placebo low caloric formula (Powder added to water). The study will continue for 6 months of intervention versus active placebo, with additional 6 months (an extension period), in which participants at both groups, the intervention and the placebo, will be offered to continue their participation in the study with the active study supplement.

In addition, 30 prepubertal healthy siblings will be recruited to the study in order to compare baseline eating and physical activity patterns of ADHD children treated with stimulants to their healthy untreated siblings at the same age range. Participants' siblings will only complete once the nutritional and physical activity questionnaire and report height and weight measurements.

Inclusion Criteria:

1. Boys aged ≤ 10 years and girls aged ≤ 9 years.
2. Children treated with stimulants medications for ADHD for at list 3 months.
3. Prepubertal -Tanner stage 1 (gonadarche) (boys: testicular volume < 4, girls: breast at Tanner stage 1)
4. Normal weight status: BMI-SDS ≤ 85th percentile for age and gender according to the CDC 2000 growth charts
5. Signing inform consent forms

Exclusion Criteria:

1. Diagnosis of GH Deficiency or treatment with GH
2. Any known chronic disease or dysmorphic syndrome including bone diseases, organic brain diseases, neurological disease, past or current malignancy, chronic cardiac, renal or pulmonary problems
3. Any known gastrointestinal disease including malabsorption
4. Any known organic reason for growth retardation
5. Milk allergy.
6. Any chronic treatment with additional medication beside stimulants that might affect appetite, weight, or growth (for example SSRI's).