title: Review: long-term impact of bariatric surgery on body weight, comorbidities, and nutritional status.
abstract: BACKGROUND
  The number of patients who undergo Roux-en-Y gastric bypass (RYGB) and gastric banding (GB) surgeries has increased dramatically over the past decade, yet the long-term impact of these surgeries on body weight, comorbidities, and nutritional status remains unclear, as do the mechanisms of weight regain.
  
  
  METHODS
  The articles were found via PubMed searches. To review the impact of bariatric surgery on weight maintenance and comorbidities, only articles with a postoperative follow-up of 3 yr or longer were included. The articles on nutritional status had a follow-up of 12 months or longer.
  
  
  CONCLUSIONS
  RYGB and GB surgeries lead to substantial weight loss in individuals with morbid obesity. However, significant weight regain occurs over the long term, and according to the only well-designed prospective controlled study, the improvement in comorbidities associated with weight loss mitigates in the long term on weight regain. There is some evidence from a retrospective study that RYGB surgery is associated with a modest decrease in long-term mortality. These results remain to be substantiated by well-designed, long-term, randomized and prospective controlled studies. The mechanisms that lead to weight regain need to be further examined and may include increase in energy intake due to enlargement of stoma and adaptive changes in the levels of gut and adipocyte hormones such as ghrelin and leptin, which regulate energy intake; decrease in physical activity; changes in energy expenditure; and other factors. In addition to weight regain, RYGB surgery is associated with frequent incidence of iron, vitamin B12, folate, calcium, and vitamin D deficiency, which requires regular supplementation and monitoring.
authors.affiliation: Division of Nutrition and Metabolic Diseases, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9052, USA.
authors.forename: Meena
authors.initials: M
authors.lastname: Shah
authors.forename: Vinaya
authors.initials: V
authors.lastname: Simha
authors.forename: Abhimanyu
authors.initials: A
authors.lastname: Garg
mesh_terms: D050110:Bariatric Surgery / Q000009:adverse effects* / Q000379:methods*; D001835:Body Weight / Q000502:physiology*; D015390:Gastric Bypass / Q000009:adverse effects; D006287:Health Planning Guidelines; D006801:Humans; D018977:Micronutrients / Q000172:deficiency; D008954:Models, Biological; D009752:Nutritional Status / Q000502:physiology*; D009767:Obesity, Morbid / Q000150:complications* / Q000601:surgery*; D011488:Protein Deficiency / Q000209:etiology; D013995:Time; D015430:Weight Gain; D015431:Weight Loss
chemical_list: D018977:Micronutrients