Ketogenic Diets for Weight Loss Maintenance: Impact on Energy Expenditure and Appetite in Individuals With Obesity (KETOWEI)

April 3, 2026 updated by: Catia Martins, University of Alabama at Birmingham
The goal of this clinical trial is to investigate whether a Ketogenic Diet (KD) can increase Total Energy Expenditure (TEE), while benefiting appetite, during weight loss maintenance in reduced-obese individuals.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The total duration of the intervention will be 10 weeks. Participants will first undergo 4 weeks of a low-energy diet (LED), aiming to induce a minimum of 5% weight loss (weight loss phase). Those who achieve at least a 5% weight loss will then be randomized (1:1) to a 6-week weight loss maintenance (WLM) diet, either a KD or an isocaloric low-fat diet, with the first 2 weeks being a gradual refeeding.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Alabama
      • Birmingham, Alabama, United States, 35294
        • Recruiting
        • University of Alabama at Birmingham
        • Contact:

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • BMI 30-45 kg/m2
  • Both men and women
  • Age between 18-65 years
  • Sedentary to moderately active (<2 h/wk of moderate, structured, intentional, exercise)

Exclusion Criteria:

  • Pregnancy or lactation
  • Daily use of tobacco (>1 pk/wk)
  • Change in weight greater than 5 lb in the previous 3 months
  • Cognitive impairment
  • Previous bariatric surgery
  • History of eating disorder
  • Presence of any condition (e.g. DM2, PCOS, inflammatory disease, untreated thyroid disease, fluid overload states such as chronic kidney disease, congestive heart failure, or cirrhosis)
  • Use of any medication (e.g., glucocorticoid, GLP-1 analogues, hormone replacement therapy) deemed to interfere with study outcomes.
  • Pre-menopausal women will need to have a regular menstrual cycle (28+/-2 days) or be on hormonal contraceptives
  • Fasting glucose plasma concentration >125 mg/dl and/or HbA1c > 6.4%

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

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Ketogenic Diet
Participants randomized to the ketogenic diet will follow a diet with 5% energy from carbohydrates, 70% from fat, and 25% from protein for 6 weeks. The first 2 of the 6 weeks weeks will be a gradual refeeding, with participants slowly withdrawing from the meal replacements used during the 4-week weight loss phase, while introducing more food.
Behavioral: Calorie Restriction
Participants will follow a commercial low-energy diet and be provided with meal replacements for 4 weeks aiming to achieve a minimum of 5% weight loss.
Behavioral: Behavioral Support
Participants will meet weekly with a registered dietitian, for a 20-minute consultation throughout the entire study period (10 weeks) to increase engagement and improve adherence and retention.
Behavioral: Diet Therapy
Participants will be provided food to meet the ketogenic diet prescription for the 6-week weight maintenance phase.
Behavioral: Diet Therapy
Participants will have food provided to meet the standard low-fat diet prescription for the 6-week weight maintenance phase.
Active Comparator: Low-Fat Diet
Participants randomized to the low-fat diet will follow a diet with 50% energy from carbohydrates, 25% energy from fat, and 25% energy from protein for 6 weeks. The first 2 of the 6 weeks weeks will be a gradual refeeding, with participants slowly withdrawing from the meal replacements used during the 4-week weight loss phase, while introducing more food.
Behavioral: Calorie Restriction
Participants will follow a commercial low-energy diet and be provided with meal replacements for 4 weeks aiming to achieve a minimum of 5% weight loss.
Behavioral: Behavioral Support
Participants will meet weekly with a registered dietitian, for a 20-minute consultation throughout the entire study period (10 weeks) to increase engagement and improve adherence and retention.
Behavioral: Diet Therapy
Participants will be provided food to meet the ketogenic diet prescription for the 6-week weight maintenance phase.
Behavioral: Diet Therapy
Participants will have food provided to meet the standard low-fat diet prescription for the 6-week weight maintenance phase.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change from baseline total energy expenditure
Time Frame: Baseline, week 6, week 10
Total Energy Expenditure (TEE) refers to the total amount of energy (calories) your body uses in a day. Twenty-four-hour EE and RQ will be measured inside the whole room indirect calorimeter (chamber) following standard procedures
Baseline, week 6, week 10

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in appetite ratings
Time Frame: Baseline, week 6, week 10
Subjective appetite ratings are personal feelings or perceptions about hunger, fullness, desire to eat (DTE), and prospective food consumption (PFC) usually measured using self-reported scales ranging from "not at all" to "extremely". Subjective appetite ratings (hunger, fullness, DTE and PFC) will be measured using a validated 10cm visual analog scale which will be given to the participants inside the chamber before meals.
Baseline, week 6, week 10
Change in total body composition
Time Frame: Baseline, week 4, week 6, week 10
Bioimpedance analysis (BIA) will be used to measure fat mass, fat-free mass, total, extra, and intra-cellular water.
Baseline, week 4, week 6, week 10
Change in total body composition
Time Frame: Baseline, week 4, week 6, week10
FM, bone mass, and lean body mass will be determined by dual-energy X-ray absorptiometry (iDXA instrument, GE Healthcare Lunar, Madison, WI) with the use of software version 1.5g (Lunar Corp).
Baseline, week 4, week 6, week10
Change in total body weight
Time Frame: Baseline, week 4, week 6, week 10
Body weight is the total amount a person weighs when measured on a scale.
Baseline, week 4, week 6, week 10
Change in resting energy expenditure
Time Frame: Baseline, week 6, week 10
Resting Energy Expenditure (REE) is the amount of energy (calories) your body needs to keep working while you're at rest. Participants will enter the chamber in the morning in the fasting state. REE will be measured while the participant is in the metabolic chamber.
Baseline, week 6, week 10
Change in mechanical efficiency
Time Frame: Baseline, week 6, week 10
Walking economy will be assessed using a submaximal treadmill test, performed 90 minutes after breakfast. Following a familiarization period, participant will walk on the treadmill at 2 miles/hour for 15 minutes, followed by another 15 minutes at 2.5 miles/hour.
Baseline, week 6, week 10
Change in fasting insulin
Time Frame: Baseline, week 6, week 10
Circulating (serum) fasting insulin will be measured using validated methods
Baseline, week 6, week 10
Change in fasting cholecystokinin
Time Frame: Baseline, week 6, week 10
Circulating (plasma) fasting cholecystokinin will be measured by RIA.
Baseline, week 6, week 10
Change in fasting ghrelin
Time Frame: Baseline, week 6, week 10
Circulating (plasma) fasting ghrelin concentrations will be measured by ELISA
Baseline, week 6, week 10
Change in fasting glucagon-like peptide-1
Time Frame: Baseline, week 6, week 10
Circulating (plasma) fasting total GLP-1 will be measured by ELISA
Baseline, week 6, week 10
Change in fasting peptide YY (PYY)
Time Frame: Baseline, week 6, week 10
Circulating (plasma) fasting PYY3-36 concentrations will be measured by ELISA
Baseline, week 6, week 10
Change in postprandial insulin
Time Frame: Baseline, week 6, week 10
Circulating (serum) insulin measured before and 30, 60, 90, and 120 minutes after intake of breakfast with validated methods
Baseline, week 6, week 10
Change in postprandial cholecystokinin
Time Frame: Baseline, week 6, week 10
Circulating (plasma) cholecystokinin measured before and 30, 60, 90, and 120 minutes after intake of breakfast with RIA.
Baseline, week 6, week 10
Change in postprandial ghrelin
Time Frame: Baseline, week 6, week 10
Circulating (plasma) ghrelin measured before and 30, 60, 90, and 120 minutes after intake of breakfast with ELISA
Baseline, week 6, week 10
Change in postprandial glucagon-like peptide-1
Time Frame: Baseline, week 6, week 10
Circulating (plasma) total GLP-1 measured before and 30, 60, 90, and 120 minutes after intake of breakfast by ELISA
Baseline, week 6, week 10
Change in postprandial peptide yy
Time Frame: Baseline, week 6, week 10
Circulating (plasma) PYY3-36 concentrations measured before and 30, 60, 90, and 120 minutes after intake of breakfast with ELISA
Baseline, week 6, week 10

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Blood work: beta hydroxybutyrate
Time Frame: Week 1, week 2, week 3, week 4, week 5, week 6, week 7, week 8, week 9, week 10
Adherence to the dietary interventions will be assessed using objective biochemical analysis through the measurement of beta hydroxybutyrate in blood using a ketone meter.
Week 1, week 2, week 3, week 4, week 5, week 6, week 7, week 8, week 9, week 10
Urine sample: acetoacetate
Time Frame: Week 1, week 2, week 3, week 4, week 5, week 6, week 7, week 8, week 9, week 10
Adherence to the dietary interventions will be assessed using objective biochemical analysis through the measurement of acetoacetate in urine using Ketostix reagent strips.
Week 1, week 2, week 3, week 4, week 5, week 6, week 7, week 8, week 9, week 10
Change in glucose
Time Frame: Baseline, week 6, week 10
The fasting blood sample collected before the participants enter the chamber will be analyzed for circulating glucose using the SIRRUS analyzer.
Baseline, week 6, week 10
Change in total cholesterol
Time Frame: Baseline, week 6, week 10
The fasting blood sample collected before the participants enter the chamber will be analyzed for circulating total cholesterol concentrations using the SIRRUS analyzer.
Baseline, week 6, week 10
Change in high-density lipoprotein cholesterol
Time Frame: Baseline, week 6, week 10
The fasting blood sample collected before the participants enter the chamber will be analyzed for circulating HDL-C using the SIRRUS analyzer.
Baseline, week 6, week 10
Change in triglycerides
Time Frame: Baseline, week 6, week 10
The fasting blood sample collected before the participants enter the chamber will be analyzed for circulating triglyceride concentrations using the SIRRUS analyzer.
Baseline, week 6, week 10
Change in free fatty acids
Time Frame: Baseline, week 6, week 10
The fasting blood sample collected before the participants enter the chamber will be analyzed for circulating free fatty acid concentrations using the SIRRUS analyzer.
Baseline, week 6, week 10
Change in average appetite
Time Frame: Baseline, week 1, week 2, week 3, week 4, week 5, week 6, week 7, week 8, week 9, week 10
Participants will be asked to report their average hunger, fullness, desire to eat and prospective food consumption (e.g. how hungry did you feel this week? how much did you think about food this week?) over the previous week using a 10-cm visual analogue scale ranging from "not at all" to "extremely".
Baseline, week 1, week 2, week 3, week 4, week 5, week 6, week 7, week 8, week 9, week 10

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Alabama at Birmingham

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 1, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 30, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 10, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 13, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 16, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 7, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 3, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • IRB-300012956
  • P30DK079626 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

This project will produce demographic information, anthropometric and body composition data, energy expenditure, fat oxidation, plasma concentrations of several gastrointestinal hormones involved in appetite regulation, insulin, glucose, blood lipids, and subjective appetite feelings. Data will be obtained from bioimpedance analysis and dual-energy x-ray absorptiometry (DEXA) for body compsoiiton; ELISA, RIA and other laboratorial methods used for the quantification of hormones and metabolites, and questionnaires and visual analogue scales. Data will be collected from 20 research participants. We estimate to be generating gigabyte (.csv) amounts of data. The methodology, statistical analysis plan, and a data dictionary will also be shared. Based on ethical considerations, scientific data will be de-identified and shared at the participant level. Data will be made available in .csv format and will not require the use of specialized tools to be accessed or manipulated.

IPD Sharing Time Frame

The data will be shared with others by the time the related study is published and will stay available for at least 10 years.

IPD Sharing Access Criteria

All datasets that can be shared will be deposited in the NIH-supported Vivli repository which specializes in clinical trial data. Given the sensitive nature of the dataset, de-identified human subjects' data will be made available in Vivli, which restricts access to the data to qualified investigators with an appropriate research question who sign a data use agreement.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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