Obesity rates have increased in recent decades, with the estimate that 78.6 million American adults are obesos (CDC, 2014). In Brazil, data show that 50.8% of the population is overweight and 17.5% obesidade (VIGITEL, 2013). Concomitant the obesity epidemic, there was the rise of bariatric surgery, and gastroplasty intestinal bypass in Roux-en-Y, the surgical technique more utilizada (SBCBM, 2014). This study aims to determine the prevalence of hair loss during the first year of post-bariatric surgery. This is a retrospective, observational study from the collection of data from medical records of patients in a private clinic in Brazil. The sample consisted of 146 patients, 133 (91.2%) women and 13 men (8.9%) with a mean age of 39 ± 10.7, undergoing gastroplasty. 3 and 6 months after surgery, the prevalence of patients with hair loss was similar, 51 (34.9%) and 52 (35.6%), respectively. While at 1 year postoperatively, a significant reduction was observed, only 14 (9.6%) of the patients had this symptom. These findings may be related to dietary changes that occur in the first months of surgery because during the first three months, the energy content of the diet does not exceed 800 kcal/day. Only after 6 months, the reservoir volume increases, allowing a higher intake. The power postoperative should follow the dietary recommendations of the food pyramid adapted to surgery bariátrica (MOIZE et al, 2010), with balance between macro and micronutrients from food and nutritional supplements to compensate for nutrient deficiency caused by surgery avoiding excessive hair loss.