Could the mechanisms of bariatric surgery hold the key for novel therapies? report from a Pennington Scientific Symposium

Abstract

Bariatric surgery is the most effective method for promoting dramatic and durable weight loss in morbidly obese subjects. Furthermore, type 2 diabetes is resolved in over 80% of patients. The mechanisms behind the amelioration in metabolic abnormalities are largely unknown but may be due to changes in energy metabolism, gut peptides and food preference. The goal of this meeting was to review the latest research to better understand the mechanisms behind the 'magic' of bariatric surgery. Replication of these effects in a non-surgical manner remains one of the ultimate challenges for the treatment of obesity and diabetes. Promising data on energy metabolism, gastrointestinal physiology, hedonic response and food intake were reviewed and discussed.

Figure 1

Schematic diagram showing flow of information potentially involved in the physiological and behavioural consequences of gastric bypass surgery. Changes in hormonal and neural signals generated by the surgery and its adaptive consequences affecting other peripheral organs and the brain are shown in red (Berthoud, Holst, Kaplan, Poires, Strader, Seeley, Hajnal) Behavioural changes such as food intake and food preference resulting from altered signalling to the brain are shown by green lines (Berthoud, Bueter, Chakravarthy, Geleibter, Seeley). Changes in autonomic and endocrine functions that feed back to the gut and other peripheral organs are shown by blue lines (Raybould). The contribution of changed energy metabolism and energy expenditure is shown in purple (Kaplan, Ravussin). Note that the arrangement allows learning to take place, as ingestion of different foods produces different consequences in the altered gut that are in turn sensed by the brain.