 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 effects on primary and secondary outcome measurements will take into account the consumption rate of the study formulaplacebo 