Bariatric surgery was originally developed with the aim of reducing the patient's intake of food and energy, thereby achieving sustainable weight reduction. Restriction and malabsorption were regarded as mechanisms of action.
Restrictive procedures are interventions in which the amount of food intake is limited. Typical examples are gastric banding and gastric sleeve procedure. Malabsorptive procedures are interventions that limit the intake of food components and lead to consciously induced deficiency digestion. This includes biliopancreatic diversion (BPD) according to Scorpino. Combined procedures are interventions in which restrictive and malabsorptive mechanisms of action occur together. The gastric bypass technique, for example, is a restrictive procedure in which slight malabsorptive effects also occur. Biliopancreatic diversion with duodenal switch is also a classic combination procedure.
The presumed mechanisms of restriction and malabsorption are increasingly being questioned since physiological effects of bariatric interventions explain the favourable results on body weight and obesity-related secondary diseases much more plausible. These include the effect of bariatric interventions on hormones produced in the gastrointestinal tract, changes in the intestinal flora and changes in the concentration of bile acids in the blood.
Further information on the various mechanisms of action of bariatric surgery:
- restriction and malabsorption
- the feeling of hunger and fullness
- gut microbiota (microbiome)
- bile acids
Bilbiography sources:
Baraboi ED, Li W, Labbé SM, Roy MC, Samson P, Hould FS, Lebel S, Marceau S, Biertho L, Richard D. Metabolic changes induced by the biliopancreatic diversion in diet-induced obesity in male rats: the contributions of sleeve gastrectomy and duodenal switch. Endocrinology. 2015 Apr;156(4):1316-29.
Browning MG, Franco RL, Cyrus JC, Celi F, Evans RK. Changes in Resting Energy Expenditure in Relation to Body Weight and Composition Following Gastric Restriction: A Systematic Review. Obes Surg. 2016 Jul;26(7):1607-15.
Bueter M, Seyfried F, Germer CT. Why patients lose weight after bariatric operations. Zentralbl Chir. 2010 Feb;135(1):28-33.
Chakravartty S, Tassinari D, Salerno A, Giorgakis E, Rubino F. What is the Mechanism Behind Weight Loss Maintenance with Gastric Bypass? Curr Obes Rep. 2015 Jun;4(2):262-8.
Corteville C, Fassnacht M, Bueter M. [Surgery as pluripotent instrument for metabolic disease. What are the mechanisms?]. Chirurg. 2014 Nov;85(11):963-8.
Dixon JB, Lambert EA, Lambert GW. Neuroendocrine adaptations to bariatric surgery. Mol Cell Endocrinol. 2015 Dec 15;418 Pt 2:143-52.
Farias G, Netto BDM, Bettini SC, Dâmaso AR, de Freitas ACT. Neuroendocrine regulation of energy balance: Implications on the development and surgical treatment of obesity. Nutr Health. 2017 Sep;23(3):131-146.
Garruti G, Di Ciaula A, Wang HH, Wang DQ, Portincasa P. Cross-Talk Between Bile Acids and Gastro-Intestinal and Thermogenic Hormones: Clues from Bariatric Surgery. Ann Hepatol. 2017 Nov;16(Suppl. 1: s3-105.):s68-s82.
Harvey EJ, Arroyo K, Korner J, Inabnet WB. Hormone changes affecting energy homeostasis after metabolic surgery. Mt Sinai J Med. 2010 Sep-Oct;77(5):446-65.
Ionut V, Burch M, Youdim A, Bergman RN. Gastrointestinal hormones and bariatric surgery-induced weight loss. Obesity (Silver Spring). 2013 Jun;21(6):1093-103. Review.
Lin C, Våge V, Mjøs SA, Kvalheim OM. Changes in Serum Fatty Acid Levels During the First Year After Bariatric Surgery. Obes Surg. 2016 Aug;26(8):1735-42.
Liu H, Hu C, Zhang X, Jia W. Role of gut microbiota, bile acids and their cross-talk in the effects of bariatric surgery on obesity and type 2 diabetes. J Diabetes Investig. 2018 Jan;9(1):13-20.
Lutz TA, Bueter M. The physiology underlying Roux-en-Y gastric bypass: a status report. Am J Physiol Regul Integr Comp Physiol. 2014 Dec 1;307(11): R1275-91.
Lutz TA, Bueter M. Physiological mechanisms behind Roux-en-Y gastric bypass surgery. Dig Surg. 2014;31(1):13-24. Review.
Miras AD, le Roux CW. Mechanisms underlying weight loss after bariatric surgery. Nat Rev Gastroenterol Hepatol. 2013 Oct;10(10):575-84.
Nimeri A. Making sense of gastric/intestinal bypass surgeries: forget the name and remember the degree of restriction and malabsorption the surgeries provide. Surg Obes Relat Dis. 2017 Apr;13(4):716-719.
Peat CM, Kleiman SC, Bulik CM, Carroll IM. The Intestinal Microbiome in Bariatric Surgery Patients. Eur Eat Disord Rev. 2015 Nov;23(6):496-503.
Sandoval D. Bariatric surgeries: beyond restriction and malabsorption. Int J Obes (Lond). 2011 Sep;35 Suppl 3: S45-9.
