The aim of this study is to investigate whether metformin has inhibitory effect on exercise-induced lipolysis in subcutaneous adipose tissue in healthy lean man. Ten healthy lean mean will follow protocols consisting of 60 minutes of exercise on bicycle ergometer combined with a) orally administered metformin and b) locally administered metformin into adipose tissue and c) without metformin treatment. Microdialysis is used for assessment of metabolites in situ in subcutaneous adipose tissue.