Tirzepatide Impact Assessment Study

Summary

This study examines how two different weight-loss strategies affect heart and metabolic health, as well as changes at the molecular level in the body. One group includes adults who are starting a GLP-1 receptor agonist medication (i.e., semaglutide or tirzepatide) prescribed by their own doctor for weight loss. The other group includes adults who will participate in a structured lifestyle program combining a reduced-calorie diet with increased physical activity. Both groups complete assessments at the start of the study and again after three months.

At each visit, participants have their weight, body composition, blood pressure, and resting metabolic rate measured. A blood draw is collected to evaluate cholesterol, blood sugar, insulin, appetite hormones, and liver and kidney function markers, and to analyze gene activity (RNA sequencing) and metabolites, which are small molecules that reflect how the body is using energy and nutrients. Participants also complete online questionnaires about diet, disordered eating, stress, mental health, and quality of life. Those in the lifestyle group attend three individual nutrition and physical activity counseling sessions over the course of the study.

The main goals of the study are (1) to determine whether GLP-1 receptor agonist medication or lifestyle changes produce greater improvements in heart and metabolic health markers over three months; (2) to examine if GLP-1 receptor agonist medication or lifestyle changes produce greater improvement in disordered eating, stress, mental health, and quality of life; (3) to investigate if GLP-1 receptor agonist medication or lifestyle changes produce greater improvement in appetite-related hormones (i.e., ghrelin, GLP-1, insulin, leptin, and peptide YY); and (4) to explore whether the two approaches cause different changes in gene expression and metabolic profiles. This is a pilot study conducted at Texas Tech University's Nutrition and Metabolic Health Initiative clinic in Lubbock, Texas.

Who can participate: Adults aged 18 years and older with a BMI of 27.5 or higher who are either starting semaglutide or tirzepatide therapy for weight management or who are seeking weight management without the use of weight-loss medications.

Who cannot participate: Individuals who are pregnant or lactating, have a pacemaker or internal medical device, have certain serious medical conditions (such as active cancer, uncontrolled hypertension, or severe kidney disease), have type 1 diabetes, or use insulin for type 2 diabetes.

Conditions

• Obesity & Overweight
• Cardiometabolic Health Indicators
• Addiction
• Eating Disorders
• Mental Health

Interventions

DRUG

GLP-1 Receptor Agonist Therapy

Participants receive semaglutide or tirzepatide as prescribed by their own medical provider prior to study enrollment. Dosing and titration followed the prescribing provider's clinical judgment and are not controlled by the study team. Both medications are GLP-1 receptor agonists approved for weight management and glycemic control; tirzepatide additionally acts on the glucose-dependent insulinotropic polypeptide (GIP) receptor.

BEHAVIORAL

Structured Lifestyle Intervention

A reduced-calorie diet providing a 500 kcal daily deficit from individually calculated total energy expenditure, combined with a goal of 150 to 300 minutes of moderate-intensity physical activity per week. Total energy expenditure is estimated by multiplying each participant's measured resting metabolic rate (MedGem indirect calorimetry) by a standard physical activity factor. Meal plans are based on the Academy of Nutrition and Dietetics Nutrition Care Manual. Three individual counseling sessions are delivered over three months in person or via a HIPAA-secured video platform.

Sponsors & Collaborators

• Texas Tech University

  lead OTHER

Study Design

Allocation

NON_RANDOMIZED

Purpose

OTHER

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2025-01-02

Primary Completion

2026-11-23

Completion

2026-12-07

Countries

• United States

Study Locations