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  • Review Article
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Mechanisms underlying weight loss after bariatric surgery

Nature Reviews Gastroenterology & Hepatology volume 10, pages 575–584 (2013)Cite this article

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Abstract

The clinical efficacy of bariatric surgery has encouraged the scientific investigation of the gut as a major endocrine organ. Manipulation of gastrointestinal anatomy through surgery has been shown to profoundly affect the physiological and metabolic processes that control body weight and glycaemia. The most popular bariatric surgical procedures are gastric bypass, adjustable gastric banding and vertical sleeve gastrectomy. Even though these procedures were designed with the aim of causing restriction of food intake and nutrient malabsorption, evidence suggests that their contributions to weight loss are minimal. Instead, these interventions reduce body weight by decreasing hunger, increasing satiation during a meal, changing food preferences and energy expenditure. In this Review, we have explored these mechanisms as well as their mediators. The hope is that that their in-depth investigation will enable the optimization and individualization of surgical techniques, the development of equally effective but safer nonsurgical weight-loss interventions, and even the understanding of the pathophysiology of obesity itself.

Key Points

  • Bariatric surgery is the most effective treatment for weight loss and its long-term maintenance; the most commonly performed procedures are laparoscopic gastric bypass, adjustable gastric banding and vertical sleeve gastrectomy

  • Bariatric surgery improves obesity-related comorbidities and reduces overall and cardiovascular mortality

  • Gastric bypass works by reducing hunger, increasing satiation, changing food preferences and increasing diet-induced energy expenditure

  • Adjustable gastric banding works probably through the reduction in hunger, which might be mediated through vagal signalling

  • Some of the clinical and physiological effects of vertical sleeve gastrectomy are similar to gastric bypass

  • Understanding the mechanisms of action of these procedures could accelerate their optimization and the development of novel, and hopefully safer, medications for obesity and type 2 diabetes mellitus

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Figure 1: Anatomical changes in bariatric surgery.
Figure 2: Schematic representation of the physiological mechanisms that underlie weight loss and glycaemic improvements after gastric bypass surgery, which has been studied more extensively compared with the other available surgical procedures.

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Acknowledgements

A. D. Miras is funded by the Medical Research Council (MRC) Research Training Fellowship G0902002 and a MRC Research Career Development Centenary Award. C. W. le Roux is funded by the Science Foundation Ireland and the Moulton Foundation.

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  1. Molecular and Metabolic Imaging Group, Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital, London, W12 0NN, UK

    Alexander D. Miras

  2. Diabetes Complications Research Centre, UCD Conway Institute, School of Medicine and Medical Science, University College Dublin, Dublin, 4, Ireland

    Carel W. le Roux

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Miras, A., le Roux, C. Mechanisms underlying weight loss after bariatric surgery. Nat Rev Gastroenterol Hepatol 10, 575–584 (2013). https://doi.org/10.1038/nrgastro.2013.119

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