Our study is a double-blind, placebo-controlled, 4-week trial to investigate the effect of hypocaloric diet alone or coupled to EC treatment of morbidly obese women on thermogenesis, expression of UCP 3 (in muscle tissue) and of beta-3 adrenoreceptors (in adipose tissue). Subjects are randomly assigned to EC (200/20 mg) or to placebo administered three times a day orally together with a energy-deficit diet (70% of resting energy expenditure), starting one month before undergoing bariatric surgery. Primary study endpoints are weight change analysed by intention to treat, changes in resting energy expenditure, UCP3 (long and short isoform), messenger ribonucleic acid (mRNA) levels in rectus abdominis and immunostaining for beta-3 adrenoreceptors in subcutaneous and omental adipose tissue. Also plasma epinephrine, norepinephrine, triglycerides, free fatty acids, glycerol, TSH, free thyroxine (fT4), free triiodothyronine (fT3) fasting glucose, insulin and homeostasis model assessment (HOMA) index, are measured at baseline and at the end of treatments.