This is a randomized, control trial to investigate the effect and safety of Phentermine in patients with obesity who need a bariatric surgery (BMI \>35 kg/m2 with comorbidities or BMI \> 40 kg/m2).
Screening will be made to select eligible participants before intervention. Participants were randomly assigned to one of two groups (low-calorie diet + phentermine 15 mg or low-calorie diet + placebo) for therapies during 6 weeks. Anthropometric measurements (weight, body composition, body mass index and waist-hip index), serum metabolic profile (glucose, total cholesterol, HDL-c, LDL-c, triglycerides, and HOMA-IR) markers of inflammation (IL-1, IL-6 and PCR) and hepatic ultrasound will be measured 2 times for each participant. Surgical complications (anastomosis filtration, intestinal obstruction or stenosis, need to perform open surgery and mortality) will be evaluated. Adverse events associated with phentermine (blood pressure, cardiac frequency, headache, gastrointestinal symptoms, euphoria, anxiety and insomnia) will be collected.