Users of hormonal long-acting reversible contraception (LARC) report weight gain as a side effect, but few studies have assessed body composition change among LARC users. We evaluated weight and body composition of healthy women using the levonorgestrel intrauterine system (LNG-IUS), copper intrauterine device (copper IUD) or etonogestrel implant (ENG implant). We hypothesized that weight gain and body composition over 12 months would not differ between copper IUD, LNG-IUS and ENG implant users. Study design: We performed a prospective cohort study of a subgroup of women enrolled in the Contraceptive CHOICE Project who initiated the LNG-IUS, copper IUD or ENG implant. Inclusion criteria included lack of metabolic and eating disorders or change in body weight of more than 5% in the 6 months before enrollment. We measured changes in weight and body composition (body fat percentage, total body fat mass, total lean mass and total body mass) in women who continued their method for 12 months. Results: We analyzed data from 149 participants: 85 LNG-IUS users, 31 copper IUD users and 33 ENG implant users. The mean age was 25.9 years, 56.4% were White, 82.5% had some college education and 67.6% were nulliparous. Although lean body mass increased over 12 months in LNG-IUS and copper IUD users but not in ENG implant users, changes in body weight and body composition did not differ between the groups. In the adjusted model, Black race was associated with change in total body mass (p<.05). Conclusions: Among those who continued the method for 12 months, changes in body weight and composition did not differ between copper IUD, LNG-IUS and ENG implant users. (C) 2017 Elsevier Inc. All rights reserved.954382389Coordination for the Improvement of Higher Education Personnel foundation, Ministry of Education of Brazil [99999.003163/2015-2016]Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD) [K23HD070979]