Study design:

Double blind, randomized, placebo controlled study. Participants 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.

The primary objective of the study is to assess the effect of 6-12 months treatment with nutritional supplementation standardized formula, in short and lean boys adolescents on weight Standard Deviation Score (SDS) and height SDS The Secondary Objectives of the study are to assess the effect of 6-12 months treatment with nutritional supplementation standardized formula, in short and lean boys adolescents on BMI SDS, growth velocity, time to puberty, quality of life and self-esteem The study will continue for 6 months of intervention versus active placebo, with additional optional 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 study supplement. All analyses of the effect's on primary and secondary outcome measurements will take into account the consumption rate of the study formula/placebo

Inclusion Criteria:

• Boys aged ≥10years old
• Prepubertal - Tanner stage 1 (gonadarche) (testicular volume<4)
• Height and weight ≤ 10th percentile for age and gender.
• Height-SDS ≥ -2.5 SDS
• BMI-SDS>-3 SDS
• Low proportion between weight and height
• Signing inform consent forms

Exclusion Criteria:

• Diagnosis of Growth Hormone (GH) Deficiency or treatment with GH
• 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
• Any known gastrointestinal disease including malabsorption
• Any known organic reason for growth retardation