Weight Loss and Adipose Tissue Metabolism During Conservative Treatment of Obesity (4FAT)

March 3, 2026 updated by: Sini Heinonen, University of Helsinki

Adipose Tissue Metabolism in Obesity and Diet-Induced Weight Loss: A Prospective Observational Study of Body Weight, Fat Distribution, and Tissue-Specific Metabolic Adaptations

This prospective observational study investigates weight loss and metabolic changes in adults with obesity undergoing standard clinical diet-induced lifestyle treatment and counseling. Participants follow a very-low-calorie diet followed by a conventional weight loss diet in addition to lifestyle counseling and are followed for 12 months. The study examines weight loss as the primary outcome and characterizes changes in body composition, fat distribution, glucose metabolism, inflammation, and adipose tissue biology as secondary outcomes.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Obesity is associated with metabolic complications including insulin resistance, fatty liver disease, dyslipidaemia, and systemic inflammation. Weight loss can improve these complications, yet individuals vary widely in weight loss, fat distribution and metabolic response. Subcutaneous adipose tissue dysfunction, including impaired mitochondrial biogenesis and increased inflammation, is thought to play a central role.

This prospective observational study follows adults with obesity undergoing standard-of-care diet and lifestyle treatment at Helsinki University Central Hospital, Helsinki, Finland. The intervention consists of a very-low-calorie diet for approximately 10 weeks, followed by gradual transition to a conventional weight loss diet and multidisciplinary clinical follow-up.

Assessments are performed at baseline, 6 months, and 12 months and include anthropometry, body composition (BIA, DXA), fasting blood samples, and oral glucose tolerance testing. Subcutaneous adipose tissue biopsies are obtained from four anatomical depots (gluteal, abdominal, breast, and upper arm) for molecular, mitochondrial, epigenetic, and histological analyses.

The primary outcome is diet-induced weight loss over 12 months. Secondary outcomes include changes in fat distribution, insulin sensitivity, lipid profile, inflammation, mitochondrial measures in adipose tissue, and depot-specific adipose tissue characteristics.

Study Type

Observational

Enrollment (Actual)

22

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Patients seeking treatment for obesity at Helsinki University Central Hospital and affiliated outpatient obesity clinics.

Description

Inclusion Criteria:

  • Age ≥18 years
  • BMI ≥28 kg/m²
  • Seeking treatment for obesity at Helsinki University Central Hospital or affiliated units

Exclusion Criteria:

  • Pregnancy or lactation
  • Current smoking
  • Anemia (Hb <130 g/L in men; <120 g/L in women)
  • Severe comorbid disease or condition judged by investigator to compromise safety
  • Contraindications to MRI (e.g., metal implants, claustrophobia)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Diet-Induced Weight Loss Cohort
Adults with obesity undergoing standard clinical diet treatment including a very-low-calorie diet followed by transition to a conventional weight loss diet and lifestyle counseling
Behavioral: Diet-Induced Weight Loss Program
Standard clinical obesity treatment consisting of a very-low-calorie diet for approximately 10 weeks followed by transition to a conventional weight loss diet with multidisciplinary clinical follow-up.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Percent Total Body Weight Loss (%TWL)
Time Frame: Baseline to 6 months
Percentage change in body weight from baseline, calculated as 100 × (baseline weight - follow-up weight) / baseline weight
Baseline to 6 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Body Weight (kg)
Time Frame: Baseline to 6 and to 12 months
Absolute change in body weight measured in kilograms (kg). Reported as mean change from baseline.
Baseline to 6 and to 12 months
Change in Total Body Fat Mass (kg)
Time Frame: Baseline to 6 months and to 12 months
Change in total body fat mass measured by body impedance analysis (BIA). Reported as mean change from baseline (kg).
Baseline to 6 months and to 12 months
Change in Body Fat percentage (%)
Time Frame: Baseline to 6 and to 12 months
Change in fat percentage measured by body impedance analysis (BIA). Reported as mean change from baseline (%).
Baseline to 6 and to 12 months
Change in Plasma Glycated Hemoglobin (HbA1c)
Time Frame: Baseline to 6 months and to 12 months
HbA1c plasma glycated hemoglogin measured in SI units mmol/mol, Reported as mean change from baseline.
Baseline to 6 months and to 12 months
Change in HOMA-IR (Homeostatic Model Assessment of Insulin Resistance)
Time Frame: Baseline to 6 and to 12 months
HOMA-IR calculated as fasting glucose (mmol/L) × fasting insulin (mU/L) / 22.5. Reported as mean change from baseline.
Baseline to 6 and to 12 months
Change in Plasma Total Cholesterol (mmol/L)
Time Frame: Baseline to 6 months and to 12 months
Change in Plasma Total Cholesterol (mmol/L), Reported as mean change from baseline.
Baseline to 6 months and to 12 months
Change in Plasma LDL Cholesterol (mmol/L)
Time Frame: Baseline to 6 months and to 12 months
Change in Plasma LDL Cholesterol (mmol/L). Reported as mean change from baseline.
Baseline to 6 months and to 12 months
Change in Plasma HDL Cholesterol (mmol/L)
Time Frame: Baseline to 6 months and to 12 months
Change in HDL Cholesterol (mmol/L). Reported as mean change from baseline.
Baseline to 6 months and to 12 months
Change in Plasma Triglycerides (mmol/L)
Time Frame: Baseline to 6 months and to 12 months
Change in Plasma Triglycerides (mmol/L). Reported as mean change from baseline.
Baseline to 6 months and to 12 months
Change in Plasma C-Reactive Protein Concentration (mg/L)
Time Frame: Baseline, to 6 months and to 12 months
Change in Plasma high-sensitivity C-Reactive Protein Concentration (hs-CRP, mg/L). Reported as mean change from baseline.
Baseline, to 6 months and to 12 months
Change in Mitochondrial DNA amount in Subcutaneous Abdominal Adipose Tissue
Time Frame: Baseline to 6 months and to 12 months
Change in Mitochondrial DNA Amount in Subcutaneous Abdominal Adipose Tissue, measured by qPCR as the ratio of mitochondrial to nuclear genes. Reported as a mean change from baseline.
Baseline to 6 months and to 12 months
Change in Mitochondrial DNA amount in Subcutaneous Breast Adipose Tissue
Time Frame: Baseline to 6 months and to 12 months
Change in Mitochondrial DNA Amount in Subcutaneous Breast Adipose Tissue, measured by qPCR as the ratio of mitochondrial to nuclear genes. Reported as a mean change from baseline.
Baseline to 6 months and to 12 months
Change in Mitochondrial DNA amount in Subcutaneous Upper Arm Adipose Tissue
Time Frame: Baseline to 6 months and to 12 months
Change in Mitochondrial DNA Amount in Subcutaneous Upper Arm Adipose Tissue, measured by qPCR as the ratio of mitochondrial to nuclear genes. Reported as a mean change from baseline.
Baseline to 6 months and to 12 months
Change in Mitochondrial DNA amount in Subcutaneous Lateral Upper Thigh Adipose Tissue
Time Frame: Baseline to 6 months and to 12 months
Change in Mitochondrial DNA Amount in Subcutaneous Lateral Upper Thigh Adipose Tissue, measured by qPCR as the ratio of mitochondrial to nuclear genes. Reported as a mean change from baseline.
Baseline to 6 months and to 12 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Helsinki

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 19, 2014

Primary Completion (Actual)

August 17, 2016

Study Completion (Actual)

August 17, 2016

Study Registration Dates

First Submitted

January 21, 2026

First Submitted That Met QC Criteria

March 3, 2026

First Posted (Actual)

March 6, 2026

Study Record Updates

Last Update Posted (Actual)

March 6, 2026

Last Update Submitted That Met QC Criteria

March 3, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • HUS71/13/03/01/14

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data are not publicly shared due to data protection regulations; anonymized data may be available upon reasonable request after study completion.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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