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Taking people in CanadaPhase 4

Comparing how tirzepatide and semaglutide affect energy use in adults with obesity

Compares tirzepatide with semaglutide for energy balance in adults with obesity.

Key facts

Who runs it
McMaster University
Where
Hamilton, CanadaSee the site
Trial code
Registry title
Mechanisms of Weight Loss: Tirzepatide vs Semaglutide
Status
Recruiting
Phase
Phase 4
People taking part
80 people, planned
Started
31 Oct 2026
Expected to end
31 Dec 2029
Type of study
Interventional, 2 groups
Treatments tested
  • Tirzepatide
  • Semaglutide
Record updated
28 October 2026

Who can take part

AI summary

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for adults aged 18 to 60 with obesity who do not have diabetes. It compares tirzepatide with semaglutide for 12 weeks.

Age
18 to 60 years
Sex
All sexes can join.
Disease stage
Obesity with a body mass index (BMI) above 30 kg/m2 and a stable body weight (less than 5 kg (11 lb) change in the 3 months before screening).
Earlier treatment
No glucose-lowering or weight loss drugs in the last 3 months or planned in the next 3 months. No past or planned bariatric surgery.

Main reasons for not taking part

  • Type 1 or type 2 diabetes, past or current
  • History of pancreatitis
  • Personal or family history of medullary thyroid cancer or multiple endocrine neoplasia 2
  • Pregnant or breastfeeding, or pregnancy within the last 6 months
  • Known liver disease other than non-alcoholic fatty liver disease, or kidney function (eGFR) below 30 mL/min/1.73 m2

The registry criteria, word for word

Show all 23 criteriaShow less

Who can take part

  • Age 18-60 years
  • Body mass index (BMI) >30 kg/m2
  • Stable body weight (<5kg change in the 3 months prior to screening)

Who cannot take part

  • Prior or planned bariatric surgery or planned low calorie meal program in the next 3 months
  • Known clinically significant gastric emptying abnormality (for example, severe gastroparesis or gastric outlet obstruction) or chronic GI symptoms (nausea, vomiting, diarrhea, constipation, bloating or unexplained abdominal pain) or chronically take drugs that directly affect GI motility
  • Currently pregnant/breastfeeding, previous pregnancy within the last 6 months, or unwillingness to use contraception for 3 months
  • Participation in any intervention clinical study within 90 days before screening
  • History of type 1 or type 2 diabetes or current diagnosis
  • History of pancreatitis
  • Personal or family history of medullary thyroid cancer or multiple endocrine neoplasia 2
  • Other medications, allergies or comorbidities that, in the opinion of the investigator could interfere with study medication or study measures (e.g., catecholamine medications) or current medication use that has been unstable in the past 8 weeks or expected to change within the next 3 months
  • History of cardiac conditions that precludes exercise
  • History of eating disorder within the last year
  • Glucose-lowering or weight loss drugs in the last 3 months or planned in the next 3 months
  • Known liver disease other than non-alcoholic fatty liver disease, or ALT >3x ULN
  • Estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m2
  • Intake of standard alcoholic drinks more than 21/week for men, or 14/week for women
  • Claustrophobia precluding a 24 hour stay in a whole room calorimeter or MRI scan
  • Inability to undergo MRI (weight >250 kg, incompatible implanted device, e.g., pacemaker)
  • Use of cannabis or its related products (d-9-THC, CBD, d-8-THC, and cannabinol) in the past three months
  • Use of nicotine/tobacco that has been unstable in the past 8 weeks or expected to change within the next 3 months (exclusion from MRI visit ONLY)
  • Known monogenic, syndromic hypothalamic causes of obesity
  • Not able to communicate in English

Check if you might fit

Answer for yourself. This is not a decision: only the study team can say whether you can take part.

  • Are you between 18 and 60 years old?

Where in Canada

  • McMaster UniversityHamilton, CanadaContact: Autumn Lawrence, MScTaking people

About the trial

What the trial wants to find out

The goal of this clinical trial is to determine if there are differences in the effect of 12 weeks of tirzepatide versus semaglutide on energy balance in adults with obesity and without known diabetes. The main questions it aims to answer are:

Read full original descriptionShow less

- Does tirzepatide have a greater effect on energy expenditure or energy extraction than semaglutide?

Participants will:

* Take tirzepatide or semaglutide once weekly for 12 weeks * Undergo identical baseline and week 12 study visits (including 24-hour whole room indirect calorimeter testing, MRI scan, body composition, 3-day meal plan and stool collection)

The 2 groups in the trial

  • SemaglutideTreatment being tested

    This group will take semaglutide once weekly for 12 weeks. Participants will be started at 0.25 mg and increase by one dose level every 4 weeks, if tolerated (allowing up to 3 dose levels over 12 weeks), to a maximum dose of 1 mg. Dose levels are 0.25 mg, 0.5 mg, 1 mg.

  • TirzepatideTreatment being tested

    This group will take tirzepatide once weekly for 12 weeks. Participants will be started at 2.5 mg and increase by one dose level every 4 weeks, if tolerated (allowing up to 3 dose levels over 12 weeks), to a maximum dose of 7.5 mg. Dose levels are 2.5 mg, 5 mg, 7.5 mg.

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov.
Official title
Mechanisms of Weight Loss Due to Dual GIP GLP-1 Receptor Agonism With Tirzepatide Compared to Semaglutide: A Randomized Controlled Trial
Plain-language title
Comparing how tirzepatide and semaglutide affect energy use in adults with obesityGenerated from the registry record. The registry title is the official one.
AI summary
From the trial's eligibility criteria. Read by machine on 12 November 2026.
Fit questions
Built from NCT07900074, who can take part
Record updated
28 October 2026