Applied nutritional investigation Medical weight loss versus bariatric surgery: Does method affect body composition and weight maintenance after 15% reduction in body weight? Michelle G. Kulovitz Ph.D. a, * , Deborah Kolkmeyer M.S. b , Carole A. Conn Ph.D. a , Deborah A. Cohen D.C.N. a , Robert T. Ferraro M.D. b a Department of Individual, Family, and Community Education, University of New Mexico, Albuquerque, New Mexico, USA b Southwest Endocrinology Associates, Albuquerque, New Mexico, USA article info Article history: Received 15 January 2013 Accepted 11 June 2013 Keywords: Bariatric surgery Weight loss Body composition Obesity Weight maintenance Lean mass Fat mass abstract Objective: The aim of this study was to investigate body composition changes in fat mass (FM) to lean body mass (LBM) ratios following 15% body weight loss (WL) in both integrated medical treatment and bariatric surgery groups. Methods: Obese patients (body mass index [BMI] 46.6  6.5 kg/m 2 ) who underwent laparoscopic gastric bypass surgery (BS), were matched with 24 patients undergoing integrated medical and behavioral treatment (MT). The BS and MT groups were evaluated for body weight, BMI, body composition, and waist circumference (WC) at baseline and after 15% WL. Results: Following 15% body WL, there were significant decreases in %FM and increased %LBM (P < 0.0001). Additionally, both groups saw 76% of WL from FM, and 24% from LBM indicating a 3:1 ratio of FM to LBM loss during the first 15% reduction in body weight. Finally, no significant dif- ferences (P ¼ 0.103) between groups for maintenance of WL at 1 y were found. For both groups, baseline FM was found to be negatively correlated with percentage of weight regained (%WR) at 1 y post-WL (r ¼0.457; P ¼ 0.007). Baseline WC and rate of WL to 15% were significant predictors of %WR only in the BS group (r ¼ 0.713; P ¼ 0.020). Conclusion: If followed closely by professionals during the first 15% body WL, patients losing 15% weight by either medical or surgical treatments can attain similar FM:LBM loss ratios and can maintain WL for 1 y. Ó 2014 Elsevier Inc. All rights reserved. Introduction With obesity rates and corresponding health risks rising each year, health professionals have been dedicated to understanding the physiological mechanisms of weight loss (WL), as well as the ability to keep their patients’ weight stable following significant WL [1]. According to the National Heart, Lung, and Blood In- stitute’s (NHLBI) current guidelines for clinicians, successful WL for obese individuals is defined as a 10% reduction in initial body weight that is maintained for at least 1 y [1–4]. Current research has stated that maintaining WL for >1 y using inte- grated medical treatment or bariatric surgery (BS) is largely predicted by a high baseline fat mass (FM), in conjunction with other metabolic factors, that favor the preservation of lean body mass (LBM) as percentage of body weight (%LBM) [5–11]. Un- derstanding the differences between therapeutic approaches to losing excess weight for obese individuals is important to determine if there are differences in predictors of sustained WL. Currently, limited research exists comparing WL approaches through the use of integrated medical and behavioral treatment (MT) and the use of laparoscopic gastric bypass BS. The use of BS increased nearly sixfold between 1990 and 2000 in the United States, averaging from 2.4 to 14.1 per 100,000 adults [4]. Currently, BS serves as one of the fastest and most effective WL techniques for severely obese individuals that can maintain a significant loss of weight over time [3,5]. Existing research has found that gastric bypass BS patients can lose an MGK was responsible for design and concept of project, imputing data collected, writing manuscript, creating figures, interpretation of data, and sta- tistical analysis of data. CAC was responsible for design and concept of project, interpretation of data, editing and writing of manuscript. DA was responsible for design and concept of project, data collection, and editing and writing manu- script. DC was responsible for editing and writing manuscript as well as inter- pretation of data. RTF was responsible for editing manuscript. * Corresponding author. Tel.: þ1 505 277 2658; fax: þ1 505 277 6227. E-mail address: mkulovi@unm.edu (M. G. Kulovitz). 0899-9007/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.nut.2013.06.008 Contents lists available at ScienceDirect Nutrition journal homepage: www.nutritionjrnl.com Nutrition 30 (2014) 49–54