Effect of a Low-carbohydrate Diet on Weight Loss in People Using the Injectable GLP-1 Agonist Semaglutide for Weight Loss

Effect of a Low-carbohydrate Diet on Weight Loss in People Using the Injectable GLP-1 Agonist Semaglutide for Weight Loss: a Pilot Trial

The goal of this clinical trial is to determine the effect of a low carbohydrate higher protein diet, modelled after the Atkins program on weight loss, glycemic control, risk markers of cardiovascular disease and body composition in patients taking semaglutide.

Participants will:

• Be randomized to follow either a low carb, higher protein diet or a low fat diet for 3 months.
• Visit the clinic at week 2, 4, 8 and 12 to meet with a dietician, fill out a symptoms questionnaire and for bloodwork
• Complete 3-day food records 4 times over the 12 weeks.

Study Overview

• Status: Completed
• Conditions: Weight Loss
• Intervention / Treatment: Behavioral: Low Carbohydrate; Behavioral: Low Fat

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5C2N8
      • INQUIS Clinical Research

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Aged 18-75 years, inclusive
• Overweight or obese individuals with a BMI ≥26 kg/m²
• Non-pregnant, non-lactating individuals who are not planning on becoming pregnant during the trial and are using an effective method of contraception, as outlined: (a) Complete abstinence from intercourse two weeks prior to administration of the study product, and throughout the clinical trial. Participants utilizing this method must agree to use 2 alternate methods of contraception (see d) if they should become sexually active and will be queried on whether they have been abstinent at each study visit. b) Has a male sexual partner who is surgically sterilized prior to the Screening Visit and is the only male sexual partner for that Participant; c) Sexual partner(s) is/are exclusively female; d) Use of two acceptable methods of contraception, such as a spermicide, mechanical barrier (e.g. male condom, female diaphragm), tubal ligation, contraceptive pill, intrauterine device (IUD) or contraceptive implant. The Participant must be using these methods for at least 1 week prior to the screening visit and throughout their participation in the trial.
• Started semaglutide injections for weight loss 14 to 35 days prior to screening, inclusive, are tolerating it and are willing to continue taking it
• HbA1c ≤7.5%
• Not taking any hypoglycemic agent, apart from a semaglutide
• Systolic blood pressure <160 mmHg and diastolic blood pressure <100 mmHg
• Serum creatinine <180 mmol/L (<2.1 mg/dL)
• Serum triglycerides <9 mmol/L (<800 mg/dL)
• ALT or AST <3 times the upper limit of normal
• Untreated LDL-cholesterol <5.00 mmol/l (<193 mg/dL)
• No major illness, trauma or surgery requiring hospitalization within 3mo of the screening visit
• Ability to understand the study procedures and willing to provide informed consent to participate in the study
• Subjects must be eligible to receive income in Canada and be covered by a health insurance plan such as OHIP
• Subjects are willing to sign the informed consent prior to any procedures conducted

Exclusion Criteria:

• Failure to meet any one of the inclusion criteria
• High alcohol consumption (>14 standard drinks per week or >4 standard drinks per day for males; and > 7 standard drinks per week or >3 standard drinks per day for females), with 1 standard drink defined as containing approximately 14g of pure alcohol. Examples of 1 standard drink include: 12 oz of regular beer (approx. 5% alcohol), 5 oz of wine (approx. 12% alcohol) or 1.5 oz of distilled spirits (approx. 40% alcohol)
• Individuals with a history of bariatric surgery, gastrointestinal disease, any other medical conditions or use of supplements or medications that increase risk to the subject or others or may affect the results, as judged by the Principal Investigator
• Unwillingness or inability to comply with the experimental procedures and to follow INQUIS safety guidelines
• Known intolerance, sensitivity, or allergy to any ingredients in the study test products
• Subject is currently participating or recently (within 30 days of screening) participated in a clinical trial involving long-term exposure (greater than 24 hours) to an investigational drug, nutritional supplement, or lifestyle modification

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Low Carbohydrate; Subjects randomized to the low-carbohydrate arm will be instructed on a reduced calorie diet (<1400 kcal/day) consisting of an average macronutrient distribution of 20% carbohydrate, 30% protein and 50% fat with a maximum intake of 40g/day of available (net) carbohydrates (approximately 65-75g total carbohydrates). To complement the provided low carbohydrate shakes and snacks, dietary counselling will focus on choosing sources of protein and non-starchy vegetables	Behavioral: Low Carbohydrate; Low carbohydrate diet
Active Comparator: Low Fat; Subjects randomized to the low-fat arm will be instructed on a reduced calorie diet (<1400 kcal/day) consisting of an average macronutrient distribution of 50% carbohydrate, 20% protein and 30% fat, with a maximum intake of 50g/day of fat. To complement the provided low fat shakes and snacks, dietary counselling will focus on choosing lean sources of protein and carbohydrates, while limiting high fat foods such as oils, nuts, full fat dairy, and fatty meats.	Behavioral: Low Fat; Low fat diet

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body weight	Percentage change from baseline of body weight	12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
BMI	Change from baseline of BMI	12 weeks
Fat Mass	Change from baseline of Fat Mass	12 weeks
Fasting plasma glucose	Change from baseline of fasting plasma glucose	12 weeks
Fat-free mass	Change from baseline of Fat-Free Mass	12 weeks
Skeletal Muscle Mass	Change from baseline of Skeletal Muscle Mass	12 weeks
Fasting serum insulin	Change from baseline of fasting serum insulin	12 weeks
Insulin sensitivity index	Change from baseline of HOMA-IR	12 weeks

Collaborators and Investigators

• Sponsor: INQUIS Clinical Research
• Collaborators: Simply Good Foods USA, Ltd.
• Investigators: Study Director: Janice Campbell, INQUIS Clinical Research

Study record dates

Study Major Dates

• Study Start (Actual): September 12, 2024
• Primary Completion (Actual): October 14, 2025
• Study Completion (Actual): November 30, 2025

Study Registration Dates

• First Submitted: December 1, 2025
• First Submitted That Met QC Criteria: December 1, 2025
• First Posted (Actual): December 12, 2025

Study Record Updates

• Last Update Posted (Actual): February 18, 2026
• Last Update Submitted That Met QC Criteria: February 13, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Semaglutide; GLP-1 agonist; Ozempic; Wegovy
• Additional Relevant MeSH Terms: Body Weight; Body Weight Changes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Weight Loss; Therapeutics; Diet, Food, and Nutrition; Physiological Phenomena; Nutritional Physiological Phenomena; Diet Therapy; Nutrition Therapy; Diet; Diet, Fat-Restricted
• Other Study ID Numbers: INQ-2411

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Permission has not been sought to do so. Not shared to protect personal health information and participant identity.

Drug and device information, study documents

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