Acute and Chronic Effects of Obesity (ACEO)

The goal of this study is to understand if there are differences in the fat, muscle and metabolism of individuals who developed obesity during childhood versus those who developed obesity in adulthood. We will do this by having recruited participants undergo subcutaneous adipose tissue biopsies in the abdomen and thigh, a muscle biopsy in the thigh, collect blood and urine samples, a DEXA scan and 3 submaximal exercise tests. participants will also have their resting energy expenditure measured through indirect calorimetry to tailor a targeted weight loss protocol through caloric restriction and cardiovascular exercise (3 times a week). After 10% of weight loss is completed, study participants will repeat all tests during a 2 week weight stabilization period. At 12 weeks into the intervention, indirect calorimetry, DEXA scan and blood tests will be repeated.

Study Overview

• Status: Recruiting
• Conditions: Lipid Metabolism; Metabolism Changes; Obesity & Overweight
• Intervention / Treatment: Behavioral: Weight loss

• Study Type: Observational
• Enrollment (Estimated): 150

Contacts and Locations

• Study Contact: Name: Sylvia Santosa, R.D, Ph.D; Phone Number: 5841 514-848-2424; Email: s.santosa@concordia.ca
• Study Contact Backup: Name: Kayla Toledano, Ph.D Student; Phone Number: 5145884865; Email: kayla.toledano@mail.concordia.ca

Study Locations

• Canada
  • Quebec
    • Montreal, Quebec, Canada, H4B 1R6
      • Recruiting
      • Concordia University PERFORM Centre
      • Contact: Sylvia Santosa; Phone Number: +1 (514) 702-8898; Email: s.santosa@concordia.ca
    • Montreal, Quebec, Canada
      • Recruiting
      • Concordia University PERFORM Centre
      • Contact: Sylvia Santosa; Phone Number: +1 (514) 702-8898; Email: s.santosa@concordia.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Sedentary or untrained individuals with body mass index between 30.0-39.9kg/m^2 (see conditions above).

Description

Inclusion Criteria:

We are recruiting two groups of sedentary or untrained males and pre-menopausal females (age 25-40 years) with body mass indices (BMI) between 30.0-39.9 kg/m^2. All participants will be required to provide a medical record and/or photographic evidence of weight at childhood (around age of 10-17 years old). Individuals with BMI between 40.0-41.9 may be included in the case that an individual with a much shorter height falls within this range, as BMI does not always properly define obesity type. Once the participant completes their DEXA scan, we will be able to more accurately assess the participant's obesity level and re-evaluate their elgibility.

Exclusion criteria:

Participants will be excluded if they are pregnant or planning to become pregnant, breast-feeding, presently using nicotine containing products (e.g. cigarettes, chewing tobacco, nicotine gum etc.), taking certain anti-depressants and anti-hypertensives. More modern medications will not need to be excluded as they don't affect weight loss or weight gain. As medication use will be screened, if the participant is using medications that do not affect our outcomes they will be included in the study. Participants will also be excluded if they have had any surgery (e.g. gastric bypass, magnetic implants) or have any conditions (e.g. iron deficiency anemia) or diseases (e.g. diabetes, cancer, IBD, history of eating disorders or mental illness) that may affect immune function and thus study outcomes, or the ability to participate in the study.

Participants must also have been weight stable for at least 2 months.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Childhood-onset obesity; Individuals who developed severe overweight or obesity during childhood (before puberty)	Behavioral: Weight loss; A conventional weight loss program will be implemented for participants to lose approximately 10% of their starting body weight
Adult-onset obesity; Individuals who developed obesity as adults	Behavioral: Weight loss; A conventional weight loss program will be implemented for participants to lose approximately 10% of their starting body weight

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Immune cell quantification	Flow cytometry will be used to quantify immune cell levels in adipose tissue	4 years
Pre-adipocyte and adipocyte characteristics	Cellular characteristics such as proliferation, differentiation and cellular senescence will measured.	5 years
Muscle and adipose tissue interaction	Cell culture interactions between myocytes and adipocytes will be evaluated to understand their interactions	5 years
Blood inflammatory markers	The inflammatory cytokines (e.g. IL6, TNFα), chemokines (e.g. monocyte chemoattractant protein-1), genomics, and adipokines (e.g. leptin, adiponectin) in blood and adipose tissue via PCR, luminex or ELISA will be measured	5 years

Collaborators and Investigators

• Sponsor: Concordia University, Montreal
• Collaborators: Montreal Children's Hospital of the MUHC
• Investigators: Principal Investigator: Sylvia Santosa, Concordia University, Montreal

Study record dates

Study Major Dates

• Study Start (Actual): April 30, 2025
• Primary Completion (Estimated): August 1, 2029
• Study Completion (Estimated): August 1, 2029

Study Registration Dates

• First Submitted: March 31, 2026
• First Submitted That Met QC Criteria: March 31, 2026
• First Posted (Actual): April 7, 2026

Study Record Updates

• Last Update Posted (Actual): April 7, 2026
• Last Update Submitted That Met QC Criteria: March 31, 2026
• Last Verified: April 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Overweight; Obesity
• Other Study ID Numbers: 10000619; RGPIN-2020-06809 (Other Grant/Funding Number: NSERC)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No