The present invention relates to the use of one or more compounds that are capable of increasing the serum level of insulin-like growth factor 1 (IGF-1) for the preparation of a therapeutical composition, in particular in the form of a food supplement, for the treatment of subjects suffering from serious fatigue and exhausting symptoms, burn-out and chronic fatigue syndrome. The same composition can also be used by patients suffering from depression, Alzheimer disease, irritated bowel syndrome, osteoporosis, type 2 diabetes, or for anti-aging, immune therapy and recovery after exercise. The composition also has a use in veterinary applications for increasing the growth and immunity in animals.