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"Dirksen, Carsten"
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Effects of bariatric surgery upon the sympathetic nervous system and hypothalamic-pituitary-adrenal axis in obese humans
by
Fenger, Mogens
,
Jørgensen, Henrik Løvendahl
,
Dirksen, Carsten
in
692/163
,
692/163/2743
,
692/163/2743/2037
2025
Human obesity is a state of hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis and dysfunction of the sympathetic nervous system (SNS). It is unclear whether weight loss will normalize this apparent dysfunction and if potential changes are of short -or long-term duration. In this study, we test how weight reduction following Roux-en-Y Gastric Bypass (RYGB) surgery affects the HPA-axis and SNS activity for a follow-up period of 2 years. We show that a ≈ 30% reduction in bodyweight following RYGB, is accompanied by an increase in circulating cortisol, and decrease in the concentrations of systemic metanephrines concomitant with a transient reduction in systolic blood pressure, and that the endocrine changes persist for at least 24 months post-surgery. The decrease in SNS activity was weakly, but significantly correlated with postoperative improvements in HbA1c. These findings suggests that the anatomical rearrangement of the gastrointestinal system by bariatric surgery, and the resulting marked decrease in body weight, have long-term impact on the autonomic nervous system. The biological significance of these findings is uncertain though it could be speculated that chronically elevated serum cortisol, may be involved in the development of osteoporosis, a well-known risk of bariatric surgery, as well as control of glucose and lipid metabolism. Furthermore, the chronic reduction in metanephrines observed, suggest that SNS depression may contribute to both a reduction in blood pressure and better glycemic control following surgery. We collectively demonstrate that RYGB surgery has an early and persisting impact on the HPA-axis and the sympathetic nervous system, and that this is associated with bodyweight reduction and improved glycemic control.
Journal Article
Cardiovascular effects of incretin-based drugs in patients with and without a history of heart failure: a protocol for a systematic review, meta-analysis and trial sequential analysis of randomised controlled trials
by
Jakobsen, Janus C
,
Hove, Jens Dahlgaard
,
Dirksen, Carsten
in
Body mass index
,
Cardiac arrhythmia
,
Cardiovascular Disease
2025
BackgroundIncretin-based drugs, including glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) and dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 RAs, are increasingly used in the management of type 2 diabetes mellitus and obesity. While these agents have shown cardiovascular benefits, their effects on both cardiovascular outcomes and cardiac structure and function remain uncertain—particularly in patients with and without a history of heart failure (HF).Methods and analysisWe will conduct a systematic review and search major medical databases (Cochrane Central Register of Controlled Trials (CENTRAL), Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica Database (EMBASE), Latin American and Caribbean Health Sciences Literature (LILACS), Science Citation Index Expanded (SCI-EXPANDED) and Conference Proceedings Citation Index-Science (CPCI-S)), as well as clinical trial registries from their inception and onwards to identify relevant randomised trials. The literature search is scheduled for July 2025. Two review authors will independently extract data and assess risk of bias. We will include randomised controlled trials assessing the effects of cagrilintide/semaglutide, liraglutide, semaglutide and tirzepatide in patients with and without a history of HF. The primary outcome will be cardiovascular mortality. Secondary outcomes will include HF hospitalisation, myocardial infarction, stroke, heart rate, systolic blood pressure, N-terminal pro B-type natriuretic peptide, left ventricular ejection fraction, left ventricular end-diastolic volume and left ventricular end-systolic volume. Data will be synthesised by aggregate data meta-analyses and trial sequential analysis. Risk of bias will be assessed with the Cochrane Risk of Bias tool, version 2, and the certainty of the evidence will be assessed by Grading of Recommendations, Assessment, Development and Evaluations (GRADE).Ethics and disseminationAs this study is a systematic review based on secondary analysis of published data, ethical approval is not required. Findings will be published in international peer-reviewed scientific journals.PROSPERO registration numberCRD420251003374.
Journal Article
Laparoscopic bariatric surgery versus any non-surgical intervention for adolescents or adults with obesity: protocol for a systematic review with meta-analysis and trial sequential analysis of randomised clinical trials
by
Petersen, Johanne Juul
,
Gluud, Christian
,
Scragg, Jadine
in
Adolescent
,
Adult
,
Bariatric Surgery
2026
IntroductionThe number of people living with obesity is increasing rapidly worldwide, and the WHO estimates approximately 5 million deaths yearly from non-communicable diseases related to elevated body mass index (BMI). The most effective treatment for weight loss is bariatric surgery, but due to the associated risks and the need for lifelong care, this is not a viable treatment for every patient. With the advent of gut-hormone-based medications to treat obesity, the effectiveness of non-surgical treatment is approaching that of surgical interventions. We therefore aim to investigate the beneficial and harmful effects of laparoscopic bariatric surgery versus any non-surgical treatment.Methods and analysisWe will conduct a systematic review with meta-analysis applying our eight-step procedure to assess thresholds for clinical significance and trial sequential analysis to mitigate the risk of random errors. To identify relevant trials, we will search for both published and unpublished trials, without any language restriction, in major medical databases (CENTRAL, MEDLINE, EMBASE, LILACS, SCI-EXPANDED and CPCI-S) and trial registries. The date range covered by the search is from database inception until final search date—within 3 months prior to submission of final results manuscript. Two review authors will independently screen references, extract data and perform risk-of-bias assessment using the Cochrane Risk of Bias Tool 2 and the Grading of Recommendations, Assessment, Development and Evaluations. We will include randomised clinical trials comparing laparoscopic surgery currently in use with any non-surgical comparator in adults or adolescents with BMI >30 kg/m2. Quasi-randomised studies or non-randomised studies will not be included. Our critical outcomes are all-cause mortality, serious adverse events and quality of life, and our important outcomes are major cardiovascular events, weight at follow-up, physical function and glycaemic control. In addition, we have two explorative outcomes: metabolic syndrome or Z-score and reported incident of alcohol abuse or other addictive disorder or self-inflicted harm.Ethics and disseminationThis review will collect and perform secondary analysis of data from publicly available sources and ethical approval is therefore not required. The findings will be published in peer-reviewed journals and presented at relevant scientific conferences. We will strive to publish with open access. Awareness will be made through social media platforms. This review aims to help clinicians in identifying best practices in the wide-spanning field of obesity treatment.PROSPERO registration numberCRD420251135341.
Journal Article
Roux-en-Y gastric bypass surgery of morbidly obese patients induces swift and persistent changes of the individual gut microbiota
by
Feng, Qiang
,
Allin, Kristine H.
,
Dirksen, Carsten
in
Anastomosis, Roux-en-Y
,
Bacteria - classification
,
Bacteria - genetics
2016
Background
Roux-en-Y gastric bypass (RYGB) is an effective means to achieve sustained weight loss for morbidly obese individuals. Besides rapid weight reduction, patients achieve major improvements of insulin sensitivity and glucose homeostasis. Dysbiosis of gut microbiota has been associated with obesity and some of its co-morbidities, like type 2 diabetes, and major changes of gut microbial communities have been hypothesized to mediate part of the beneficial metabolic effects observed after RYGB. Here we describe changes in gut microbial taxonomic composition and functional potential following RYGB.
Methods
We recruited 13 morbidly obese patients who underwent RYGB, carefully phenotyped them, and had their gut microbiomes quantified before (n = 13) and 3 months (n = 12) and 12 months (n = 8) after RYGB. Following shotgun metagenomic sequencing of the fecal microbial DNA purified from stools, we characterized the gut microbial composition at species and gene levels followed by functional annotation.
Results
In parallel with the weight loss and metabolic improvements, gut microbial diversity increased within the first 3 months after RYGB and remained high 1 year later. RYGB led to altered relative abundances of 31 species (
P
< 0.05, q < 0.15) within the first 3 months, including those of
Escherichia coli
,
Klebsiella pneumoniae
,
Veillonella
spp.,
Streptococcus
spp.,
Alistipes
spp., and
Akkermansia muciniphila.
Sixteen of these species maintained their altered relative abundances during the following 9 months. Interestingly,
Faecalibacterium prausnitzii
was the only species that decreased in relative abundance. Fifty-three microbial functional modules increased their relative abundance between baseline and 3 months (
P
< 0.05, q < 0.17). These functional changes included increased potential (i) to assimilate multiple energy sources using transporters and phosphotransferase systems, (ii) to use aerobic respiration, (iii) to shift from protein degradation to putrefaction, and (iv) to use amino acids and fatty acids as energy sources.
Conclusions
Within 3 months after morbidly obese individuals had undergone RYGB, their gut microbiota featured an increased diversity, an altered composition, an increased potential for oxygen tolerance, and an increased potential for microbial utilization of macro- and micro-nutrients. These changes were maintained for the first year post-RYGB.
Trial registration
Current controlled trials (ID
NCT00810823
,
NCT01579981
, and
NCT01993511
).
Journal Article
Weight-Neutral Health Intervention (WIN) for adults with BMI ≥30 kg/m2: protocol for a single-arm feasibility study
by
Dirksen, Carsten
,
Specht, Ina Olmer
,
Overbeck, Gritt
in
Agonists
,
Body image
,
Body mass index
2026
IntroductionWeight stigma and internalised weight bias are associated with poor mental, social and physical health. Weight-neutral approaches prioritise well-being and sustainable health behaviours. However, the feasibility and acceptability of weight-neutral interventions remain uncertain.Methods and analysisWeight-Neutral Health Intervention (WIN) is an investigator-initiated single-arm feasibility study enrolling 56 adults with body mass index ≥30 kg/m2 in the Capital Region of Denmark. The study investigates a codesigned weight-neutral health intervention. The 6-month intervention comprises 1 preparatory session and 11 group sessions led by trained practitioners, focusing on intuitive eating, body acceptance and self-compassion; optional components include support-network events, up to three individual online sessions and access to ‘size-inclusive yoga’ and ‘body competence’ courses. The primary feasibility outcome is follow-up completion. Recruitment proportion and adherence are secondary feasibility outcomes. These will be assessed using a set of predefined ‘traffic-light’ stop/go progression criteria. Exploratory feasibility outcomes include data completeness for other outcomes and participant engagement with the intervention. Exploratory clinical outcomes include questionnaire data (quality of life, depression, weight bias internalisation, eating behaviours, self-esteem, body image, stress and life satisfaction), clinical measures (weight, heart rate and blood pressure), biomarkers (blood samples and hair cortisol), 7-day actigraphy (physical activity and sleep) and serious adverse events. Qualitative interviews, focus groups and fieldnotes will be used to explore acceptability and contextual factors. If progression criteria are met, the study will inform the design of a pragmatic, multicentre, randomised trial. The exploratory outcomes will inform outcome selection, setting, sample size and procedures.Ethics and disseminationApproved by the Regional Ethics Committee of the Capital Region of Denmark (H-25013213). Results will be disseminated through peer-reviewed publications, conferences and public platforms.Trial registration numberNCT06922630.
Journal Article
Intensive weight loss intervention versus usual care for adults with severe and complex obesity: the LightWAY randomised trial protocol
by
Wane, Sarah
,
Larsen, Sofus Christian
,
Dirksen, Carsten
in
Adult
,
Body Mass Index
,
Clinical Protocols
2026
IntroductionEffective treatment for clinical obesity is available but is rarely offered by healthcare systems, which often treat complications without treating the underlying cause. The LightWAY trial will investigate the clinical benefits and harms as well as cost-effectiveness of an intensive weight loss intervention compared with existing weight management programmes for people with clinical obesity.Methods and analysisLightWAY is an investigator-initiated, international, randomised, parallel-group clinical superiority trial with blinded outcome assessment. Six hundred people seeking treatment for clinical obesity (body mass index ≥35 kg/m2 with comorbidities) will be recruited in centres in the UK and Denmark and randomised 1:1 to one of two groups. The experimental group will be offered a 2-year intensive weight loss programme providing support and advice to follow a total diet replacement programme, followed by gradual transition to an energy-reduced diet in combination with increased physical activity and if needed, prescription of weight loss medication. The control group will receive usual care, typically comprising brief behavioural support for weight loss and treatment of the complications of obesity or occasionally referral to specialist weight management services. The two co-primary outcomes are cardiometabolic risk, assessed with metabolic syndrome severity Z-score, and body weight assessed at 2 years. The secondary outcomes include the Short Form-36 mental component scale, 4-metre gait speed and proportion of participants achieving ≥20% weight loss. The key adverse effects will be the proportion of participants with at least one serious adverse event, incidence of eating disorders and disproportional loss of bone mass. Incremental cost-effectiveness will be assessed over the trial period and over the lifetime through modelling.Ethics and disseminationEthical approval was granted in the UK (August 2024, 24/SC/0211) and Denmark (December 2023, H-23065222). Findings will be disseminated through peer-reviewed journals and scientific conferences and to participants in the trial and clinicians.Trial registration numberNCT06321458.
Journal Article
Bilio-enteric flow and plasma concentrations of bile acids after gastric bypass and sleeve gastrectomy
2020
Background/objectivesBile acids in plasma are elevated after bariatric surgery and may contribute to metabolic improvements, but underlying changes in bile flow are poorly understood. We assessed bilio-enteric flow of bile and plasma bile concentrations in individuals with Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) surgery compared with matched non-surgical controls (CON).Subjects/methodsFifteen RYGB, 10 SG and 15 CON underwent 99Tc-mebrofenin cholescintigraphy combined with intake of a high-fat 111In-DTPA-labelled meal and frequent blood sampling. A 75Se-HCAT test was used to assess bile acid retention.ResultsAfter RYGB, gallbladder filling was decreased (p = 0.045 versus CON), basal flow of bile into the small intestine increased (p = 0.005), bile acid retention augmented (p = 0.021) and basal bile acid plasma concentrations elevated (p = 0.009). During the meal, foods passed unimpeded through the gastric pouch resulting in almost instant postprandial mixing of bile and foods, but the postprandial rise in plasma bile acids was brief and associated with decreased overall release of fibroblast growth factor-19 (FGF-19) compared with CON (p = 0.033). After SG, bile flow and retention were largely unaltered (p > 0.05 versus CON), but gastric emptying was accelerated (p < 0.001) causing earlier mixture of bile and foods also in this group. Neither basal nor postprandial bile acid concentrations differed between SG and CON.ConclusionsBilio-enteric bile flow is markedly altered after RYGB resulting in changes in plasma concentrations of bile acids and FGF-19, whereas bile flow and plasma concentrations are largely unaltered after SG.
Journal Article
Time, money, and weight loss: a qualitative study exploring patients’ perspectives on randomization for bariatric surgery vs. an intensive non-surgical weight loss program
by
Kousgaard, Marius Brostrøm
,
Dirksen, Carsten
,
Reventlow, Susanne
in
Adult
,
Bariatric surgery
,
Bariatric Surgery - adverse effects
2025
Background
Randomized controlled trials (RCTs) are foundational in advancing medical knowledge and patient care, offering high-quality evidence on the comparative effectiveness of healthcare interventions. However, a common challenge for RCTs is the recruitment of trial participants. To understand and overcome potential obstacles in recruitment for a clinical trial (the LightBAR trial, NCT06309238) comparing the effectiveness of bariatric surgery versus an intensive weight loss program, a qualitative study was conducted.
Methods
Nine patients from the public bariatric surgery waiting list participated in focus groups at a hospital in the Capital Region of Denmark. Vignette scenarios were utilized to prompt participants to reflect on barriers and facilitators for participation. Three patients participated in a follow-up interview. Data was analyzed using thematic analysis.
Results
Analysis revealed four main themes: (1) having waited long for surgery reduced participants’ willingness to be randomized; (2) the cost of weight loss medication was a major concern for participants; (3) participants were concerned about the extra work involved in program participation; and (4) participants weighed the efficacy and potential negative side effects of surgery against those of an intensive weight loss program based on personal beliefs and experiences.
Conclusions
Tailoring the recruitment strategy to patients’ circumstances and concerns, and providing clear, patient-centered communication about the nature and potential implications of participating in the trial may improve recruitment success.
Trial registration
The LightBAR trial (NCT06309238). Registered on ClinicalTrials.gov on May 2, 2024.
Journal Article
Intensive weight loss intervention versus usual care in adults with obesity: a protocol for the LightCARE randomised clinical trial
by
Wane, Sarah
,
Larsen, Sofus Christian
,
Dirksen, Carsten
in
Adolescent
,
Adult
,
Anti-Obesity Agents - therapeutic use
2025
IntroductionTotal diet replacements (TDRs) and weight loss medications (WLMs) have proven effective in producing substantial weight loss for individuals with obesity. Evidence is lacking on whether combining these treatments is effective and cost-effective in primary care for adults with obesity class I (body mass index (BMI) 30–34.9) or uncomplicated obesity class II or higher (BMI≥35 without obesity-related disease).Methods and analysisLightCARE is a 2-year 1:1 randomised, parallel-group, clinical superiority trial with blinded outcome assessment evaluating the benefits and harms of an intensive weight loss (IWL) intervention compared with usual care for adults with obesity in Denmark and the UK. The trial will include 400 participants aged 18–60 years with obesity class I or uncomplicated obesity class II or higher. The IWL programme aims to achieve and maintain a weight loss of ≥20% through a flexible and individualised combination of TDR, behavioural support, including physical activity and sleep guidance, and WLM if needed and will continue for 2 years. The control group will receive usual care offered in each country, typically consisting of brief behavioural support for weight loss. The primary outcome is body weight 2 years after randomisation. Secondary outcomes will include the proportion of participants achieving ≥20% weight loss, Short-Form-36 Mental Component Score, 4-m gait speed and Metabolic Syndrome Severity-Z score. Serious adverse events, the incidence of eating disorders and bone mineral density will be evaluated as safety outcomes. We will also examine the cost-effectiveness of the intervention, within the trial and in the longer term through modelling. We will conduct a process evaluation to inform any future implementation.Ethics and disseminationEthical approval was granted in Denmark (December 2023, H-23051332) and the UK (August 2024, 24/SC/0210). Findings from the trial will be disseminated through peer-reviewed journals and scientific conferences.Trial registration numberNCT06321432.
Journal Article
Exaggerated release and preserved insulinotropic action of glucagon-like peptide-1 underlie insulin hypersecretion in glucose-tolerant individuals after Roux-en-Y gastric bypass
by
Hansen, Dorte L.
,
Holst, Jens J.
,
Dirksen, Carsten
in
Adult
,
Biological and medical sciences
,
Blood Glucose - metabolism
2013
Aims/hypothesis
Roux-en-Y gastric bypass (RYGB) improves glycaemic control in part by increasing postprandial insulin secretion through exaggerated glucagon-like peptide (GLP)-1 release. However, it is unknown whether islet cell responsiveness to i.v. glucose, non-glucose (arginine) and incretin hormones, including GLP-1, is altered.
Methods
Eleven severely obese glucose-tolerant individuals underwent three hyperglycaemic clamps with arginine bolus and co-infusion of either GLP-1, glucose-dependent insulinotropic polypeptide (GIP) or saline before, and at 1 week and 3 months after RYGB. In addition, an OGTT was performed before and 3 months after surgery.
Results
After RYGB, insulin sensitivity improved at 1 week and 3 months, while insulin stimulation and glucagon suppression in response to the clamp with saline co-infusion were largely unaltered. The influence of i.v. GLP-1 and GIP on insulin and glucagon secretion was also unchanged postoperatively. In response to the postoperative OGTT at 3 months, insulin and GLP-1, but not GIP, secretion increased. Furthermore, the glucose profile during the OGTT was altered, with a substantial reduction in 2 h plasma glucose and a paradoxical hypersecretion of glucagon.
Conclusions/interpretation
After RYGB, insulin hypersecretion is linked to the oral, but not the i.v., route of administration and is associated with exaggerated release and preserved insulinotropic action of GLP-1, while both the secretion and action of GIP are unchanged. The results highlight the importance of increased GLP-1 secretion for improving postoperative glucose metabolism.
Trial registration
ClinicalTrials.gov NCT01559779.
Journal Article