Intermittent Phentermine for Obesity and Body Composition

This study evaluated the effects of intermittent phentermine treatment on body fat, estimated visceral adiposity, body composition, and tolerability in adults with overweight or obesity. A total of 600 adults aged 21 to 40 years with a body mass index (BMI) between 27 and 35 kg/m² participated in a single-center, randomized, four-group clinical trial conducted at Hospital Médica Campestre in León, Guanajuato, Mexico. Participants were assigned to lifestyle modification alone or lifestyle modification combined with phentermine at doses of 15 mg, 30 mg, or 37.5 mg daily. Phentermine was administered intermittently using a schedule of three months of treatment followed by one month without medication during a 14-month observation period. All participants received nutritional guidance and physical activity recommendations. Body composition was assessed using bioelectrical impedance analysis and three-dimensional body scanning. The primary outcome was the relative percentage reduction in total body fat from baseline to Month 14. Secondary outcomes included estimated visceral adiposity, waist circumference, lean body mass, body weight, BMI, medication adherence, resting heart rate, blood pressure, treatment-emergent adverse events, and treatment discontinuation. The study aimed to evaluate the dose-response effects of intermittent phentermine on body composition and the balance between efficacy and tolerability.