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NCT07277465Completed

Role of the Microbiota in Obesity: Effect After Bariatric Surgery

Source: ClinicalTrials.gov · Last updated 18 Dec 2025

Brief summary (registry, in English)

Several studies have demonstrated that bariatric surgery is effective for inducing weight loss in obese patients. In addition, the effects of this surgery on multiple associated alterations are well known, including changes in the secretion and activity of hormones involved in appetite regulation, satiety, and energy expenditure, as well as alterations in the gut microbiota composition. However, in cases of severe obesity, recent data have challenged the prevailing view, as bacterial species associated with low microbial richness (prior to surgery) appear to change only marginally after bariatric surgery, despite significant metabolic improvements. Our objective is to examine whether gut microbiota and gastrointestinal peptides are further impaired in severe obesity and, additionally, to explore how the microbiota relates to metabolic profile or sex, as well as whether bariatric surgery may differentially correct obesity-related intestinal microbial features. To this end, we propose a prospective, interventional, translational clinical study involving a cohort of 60 obese patients (BMI \> 35 kg/m²) undergoing laparoscopic gastric bypass surgery. Patients will be grouped according to their degree of obesity to assess potential baseline differences and to evaluate the efficacy of the intervention. Furthermore, we will investigate whether these parameters differ according to metabolic profile or sex. Body composition and nutritional status will be assessed, along with cardiovascular risk factors and comorbidities (hypertension, obstructive sleep apnea syndrome, dyslipidemia, type 2 diabetes mellitus, and insulin resistance). Gastrointestinal hormones (ghrelin, GIP, GLP-1, PYY, CCK, and leptin) will be measured in serum using Luminex XMAP technology. The content and diversity of the gut microbiota will be analyzed (16S rRNA amplicon sequencing and shotgun metagenomic sequencing using Illumina MiSeq technology) in stool samples collected before and 6-12 months after surgery. Additionally, individualized dietary follow-up and assessment of participants' quality of life will be conducted.

Status (registry)
Completed
Study type
Interventional
Enrollment
60 (actual)
First submitted
30 Nov 2025
Start date
Mar 2021
Primary completion date
Jan 2025
Lead sponsor
Celia Bañuls
Diseases
Obesity
NCT number
NCT07277465

What you commit to

  • Study type: Interventional
  • Participants enrolled: 60
  • From Mar 2021 to the primary completion date, Jan 2025
  • 1 site in 1 country
  • Visits and tests: ask the trial team, the registry does not list them

Built from the registry fields of ClinicalTrials.gov. It describes the study, not your situation.

Who cannot take part

Copied verbatim from ClinicalTrials.gov and grouped by topic. Only the trial team decides who can take part.

Lab values

  • Due to the nature of the study, patients with acute or chronic inflammatory diseases, established hepatic or renal insufficiency (defined as transaminase levels ±2 SD from the mean and estimated glomerular filtration rate \[CKD-EPI formula\] \>60), neoplasic diseases, or secondary causes of obesity (e.g., hypothyroidism, Cushing's syndrome) will be excluded.

Who the study is looking for

  • Patients with a body mass index (BMI) greater than 40 kg/m² (or \> 35 kg/m² with minimum one obesity comorbidity).
  • Aged between 18 and 65 years.
  • Patients with a known duration of obesity exceeding five years, despite dietary interventions and farmacological treatment.

Age in the registry: 18 years to 65 years · Sex: All · Does not accept healthy volunteers

Full criteria on ClinicalTrials.gov

Sites (1)

Sites in registry order. Pick your city on the disease page to sort them by distance.

SiteCityCountrySite status
FISABIO
Coordinator of this site? Confirm its status
ValenciaSpainUnknown status

This page is information, not medical advice. Discuss any trial with your doctor.