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Research project Physiological and biological effects of bariatric surgery

Morbid obesity and associated diseases can be successfully treated in many cases with bariatric surgery. The effects on obesity and associated diseases are well documented, but complications occur in about 7% of cases and other changes in the body may also have an impact. The overall aim of the study is to provide a knowledge base for targeted prophylactic measures against surgical complications after bariatric surgery, and to identify tissue biology and physiological effects on abdominal wall function and bone muscle strength.

Head of project

Jeff Wennerlund
Doctoral student

Project overview

Project period:

Start date: 2022-08-01

Participating departments and units at Umeå University

Department of Surgical and Perioperative Sciences

Project description


Morbid obesity and related diseases are on the rise globally, and there is a need for effective treatment. Bariatric surgery has therefore increased in prevalence and its effects are well documented (see for example the SOReg website). However, there are other effects of bariatric surgery that may have an impact on the care and surgical decision. Acid-related complications are known but there is no consensus on prophylaxis with proton pump inhibition and when it may be appropriate. After bariatric surgery, there is often rapid weight loss with nutritional changes. The effects of this condition on muscle strength are sparsely described. After weight loss, quality of life often improves but it is known that thigh muscle mass decreases. Furthermore, little is known about what happens to the abdominal wall during weight loss, and whether abdominal wall problems are caused by obesity or by the catabolic state during the weight loss phase.


The overall aim is to create a knowledge base for targeted prophylactic measures against surgical complications after bariatric surgery and to identify tissue biology effects on abdominal wall and leg muscle strength.


To study the subgroups that benefit from preventive treatment against gastric ulcers, based on gender, age, BMI, co-morbidity and socioeconomic status, through a multi-register study.

To study how altered metabolism after bariatric surgery may affect altered abdominal wall and leg muscle strength by measuring tissue biological markers in plasma, serum, muscle and fascia, and trunk and thigh muscle strength using BioDex. Quality of life and abdominal wall pain are measured with the adapted Ventral Hernia Pain Questionnaire (VHPQ) and functional status is measured with the VAS scale and the International Physical Activity Questionnaire (IPAQ).

A semistructured interview study with qualitative content analysis describes the changes in physical activity and movement after gastric bypass and weight loss 1-3 years after surgery.


As bariatric surgery has become routine, there are more aspects to consider than the primary goals of weight loss and reduced disease burden. With a large number of patients also come complications and other secondary effects that need to be highlighted in order to provide better and more individualised and socio-economical care.



Acid-related complications after laparoscopic Roux-en-Y gastric bypass: risk factors and impact of proton pump inhibitors.
Wennerlund J, Gunnarsson U, Strigård K, Sundbom M.
Surg Obes Relat Dis. 2020 May. Epub 2020 Jan 20.

Latest update: 2023-01-24