Metabolic Surgery, Reality or Myth: Scientific Side of Obesity Pathophysiology and Management

  • Emma Rose McGlone
  • Ahmed R. AhmedEmail author


Etymologically, the term ‘bariatric surgery’ means surgery to reduce weight, deriving from the Greek ‘baros’ (heavy). It is clear however that most bariatric operations have dramatic effects on type 2 diabetes mellitus and other metabolic conditions, many of which occur independently of weight loss. Weight loss may be regarded as just one of several clinical outcomes that result from the systemic changes in nutrient metabolism conferred by operations such as Roux-en-Y gastric bypass (RYGB): hence these operations can be considered examples of ‘metabolic surgery’.

This chapter will outline the existing evidence that bariatric procedures have clinical outcomes independent of weight loss and may therefore be termed ‘metabolic’. It will then outline current understanding of the main mechanisms by which weight loss-independent changes in metabolism are conferred: caloric restriction, gut hormones, bile acids and the gut microbiome (summarised in Fig. 36.1). Finally, it will consider potential limits to the notion that bariatric surgery is purely metabolic.


Metabolic surgery Gut hormones Foregut/hindgut hypothesis Incretins/anti-incretins Bile acids Gut microbiome 


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Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Endocrinology and Investigative MedicineImperial College LondonLondonUK
  2. 2.Department of Bariatric SurgerySt Mary’s Hospital, Imperial College LondonLondonUK

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