Intermittent Fasting Versus Daily Caloric Restriction for Weight Loss

NCT03411356 | Completed DMC

• 2 other identifiers: 17-0369R01DK111622-01A1
• Study Type: interventional
• Target: 165
• Locations: 1 country
• Sites: 1

Brief Summary

The primary aim of this study is to is to determine if intermittent fasting (IMF) is an effective dietary strategy for treatment of obesity. A 1 year randomized trial will be used to compare weight loss generated by IMF versus Daily Caloric Restriction (DCR). The targeted weekly energy deficit is designed to be similar (\~30%) and a comprehensive behavioral support program will be provided to both groups. The primary outcome is weight change at the end of the 1 year intervention; follow up measures will also be obtained 6 months after completing the intervention. This study will provide robust data regarding weight loss effectiveness of IMF and will further our understanding of the impact of IMF on energy balance.

Conditions

Obesity

Outcome Measures

Primary Outcomes (1)

• Change in Body Weight

  Body weight will be measured via clinic scale.

  Baseline and weeks 4, 13, 26, 39, 52.

Secondary Outcomes (13)

• Change in Body Weight

  Week 78.

• Changes in Body Composition

  Baseline and weeks 26, 52, and 78.

• Changes in Blood Pressure

  Baseline and weeks 13, 26, 52, and 78.

• Changes in Fasting Lipids

  Baseline and weeks 26, 52, and 78.

• Changes in Insulin Sensitivity

  Baseline and weeks 26, 52, and 78.

Study Arms (2)

Daily Caloric Restriction (DCR)

ACTIVE COMPARATOR

Participants in this group will focus on daily calorie restriction as their dietary weight loss strategy.

Behavioral: Daily Caloric Restriction (DCR)

Intermittent Fasting (IMF)

EXPERIMENTAL

Participants in this group will focus on modified intermittent fasting as their dietary weight loss strategy.

Behavioral: Intermittent Fasting (IMF)

Interventions

Daily Caloric Restriction (DCR) BEHAVIORAL

Participants in this group will be given a calorie goal designed to produce a 34.3% energy deficit from estimated baseline weight maintenance energy requirements. Participants in this group will also receive a 12 month comprehensive group-based behavioral weight loss program and will be instructed in specific strategies to support DCR. Randomized groups will meet separately. Participants in this group will also be asked to increase moderate intensity physical activity to a target of 300 minutes per week.

Daily Caloric Restriction (DCR)

Intermittent Fasting (IMF) BEHAVIORAL

Participants in this group will be instructed to limit energy intake to 20% of estimated baseline energy requirements on three non-consecutive days per week, and to eat ad libitum the other 4 days per week. Participants in this group will also receive a 12 month comprehensive group based behavioral weight loss program and will be instructed in specific strategies to support IMF. Randomized groups will meet separately. Participants in this group will also be asked to increase moderate intensity physical activity to a target of 300 minutes per week.

Intermittent Fasting (IMF)

Eligibility Criteria

• Age: 18 Years - 60 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Female or Male
• Age 18-60 years
• Body Mass Index 27-46 kg/m2
• Sedentary: defined as \<150 minutes per week of voluntary exercise at moderate intensity or greater and \< 60 min per day of total habitual physical activity (i.e. work related, transportation related) at moderate intensity or greater, over the past 3 months.
• No self-report of acute or chronic disease (cardiovascular disease (CVD), diabetes, gastrointestinal disorders and orthopedic problems in particular)
• No plans to relocate within the next 12 months
• No plans for extended travel (\> 2 weeks) within the next 12 months
• No nicotine use
• Live or work within 30 minutes of the Anschutz Health and Wellness Center (AHWC) (exceptions may be made at the discretion of the Study PI on a case by case basis for highly motivated subjects).

You may not qualify if:

• Have a primary care physician (or are willing to establish care with a primary care physician prior to study enrollment) to address medical issues which may arise during screening or study procedures/interventions.
• For Females
• Not currently pregnant or lactating
• Not pregnant within the past 6 months
• Not planning to become pregnant in the next 12 months;
• Sexually active women of childbearing potential may be enrolled if they have had a tubal ligation or use a reliable means of contraception
• Diastolic blood pressure \> 100 mm of Mercury (HG) or systolic blood pressure \> 160 mm HG.
• Resting heart rate \>100
• Diabetes (fasting glucose ≥126 mg/dL or Glycated Hemoglobin (A1C) ≥6.5%)
• Undiagnosed hypo- or hyper-thyroidism (TSH outside of the normal range) or history of uncontrolled thyroid disorder. History of thyroid disease or current thyroid disease treated with a stable medication regimen for at least 6 months is acceptable.
• Hematocrit, white blood cell count or platelets significantly outside the normal reference range.
• Triglycerides \> 400 mg/dL
• LDL cholesterol \> 200 mg/dL
• Abnormal resting electrocardiogram (ECG): serious arrhythmias, including multifocal Premature Ventricular Contractions (PVC's), frequent PVC's (defined as 10 or more per min), ventricular tachycardia (defined as runs of 3 or more successive PVC's), or sustained atrial tachyarrhythmia; 2nd or 3rd degree A-V block, QTc (Q-T Corrected) interval \> 480 msec or other significant conduction defects.
• Presence or history of any metabolic or chronic health problems which would affect appetite, food intake, energy metabolism, or ability to optimally participate in the exercise component including: CVD, peripheral vascular disease, cerebrovascular disease, significant cardiac arrhythmias or cardiac valve disease, diabetes, uncontrolled hyper- or hypothyroidism, uncontrolled hypertension, cancer (within the last 5 years, except skin cancer or other cancers considered cured with excellent prognosis), HIV infection, significant gastrointestinal disorders (described below), significant pulmonary disorders (described below), significant renal, musculoskeletal, neurologic, hematologic, or psychiatric disease.

Sponsors & Collaborators

• University of Colorado, Denver: lead
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): collaborator

Study Sites (1)

Kristen Bing

Aurora, Colorado, 80045, United States

Location

Related Publications (2)

• Breit MJ, Pan Z, Ostendorf DM, Dahle JH, Catenacci VA, Creasy SA, Melanson EL. Using Time-Weighted Averages of Total Daily Energy Expenditure to Estimate Energy Intake During a Weight Loss Intervention. Obesity (Silver Spring). 2025 Nov;33(11):2093-2102. doi: 10.1002/oby.70008. Epub 2025 Aug 28.

  PMID: 40878019 DERIVED

• Catenacci VA, Ostendorf DM, Pan Z, Kaizer LK, Creasy SA, Zaman A, Caldwell AE, Dahle J, Swanson B, Breit MJ, Bing K, Wayland LT, Panter SL, Scorsone JJ, Bessesen DH, MacLean P, Melanson EL. The Effect of 4:3 Intermittent Fasting on Weight Loss at 12 Months : A Randomized Clinical Trial. Ann Intern Med. 2025 May;178(5):634-644. doi: 10.7326/ANNALS-24-01631. Epub 2025 Apr 1.

  PMID: 40163873 DERIVED

MeSH Terms

Conditions

Obesity

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Study Officials

• Victoria Catenacci, MD

  University of Colorado Anschutz Health and Wellness Center

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: January 4, 2018
• First Posted: January 26, 2018
• Study Start: December 22, 2017
• Primary Completion: August 5, 2022
• Study Completion: January 24, 2023
• Last Updated: February 17, 2026

Record last verified: 2026-02

Locations

US (1)