The present invention relates to the use of a regulatory protein RS1 fragment or a nucleic acid molecule encoding said regulatory protein RS1 fragment for the preparation of a pharmaceutical composition for the amelioration, prevention and/or treatment of a metabolic disease or a secondary disorder caused by a (pathological) modification of homeostasis, wherein said RS1 fragment is characterized in comprising at least the amino acid sequence Q-C-P (Glutamine-Cysteine-Proline) or derivatives thereof. Furthermore, the present invention relates to a method for the amelioration, prevention and/or treatment of a metabolic disease or a secondary disorder caused by a (pathological) modification of homeostasis, said method comprising administering to a patient in need of such amelioration, prevention and/or treatment a pharmaceutically active amount of a regulatory protein RS1 fragment or a nucleic acid molecule encoding a regulatory protein RS1 fragment, wherein said RS1 fragment is characterized in comprising at least the amino acid sequence Q-C-P (Glutamine-Cysteine-Proline) or derivatives thereof. Moreover, the present invention relates to the use of a regulatory protein RS1 fragment or a nucleic acid molecule encoding said regulatory protein RS1 fragment for the preparation of food and/or food supplements.