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Diet, Insulin Sensitivity, and Postprandial Metabolism (TEF)

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ClinicalTrials.gov Identifier: NCT02939638
Recruitment Status : Completed
First Posted : October 20, 2016
Last Update Posted : March 20, 2019
Sponsor:
Collaborator:
Yale University
Information provided by (Responsible Party):
Physicians Committee for Responsible Medicine

Brief Summary:
This randomized, controlled trial aims to elucidate the mechanisms by which a plant-based dietary intervention causes weight loss. Using a low-fat, plant-based diet for 16 weeks, along with an untreated control for comparison, the study will measure changes in insulin sensitivity, beta-cell function, postprandial metabolism, and intracellular lipid, and assess their associations with changes in body weight.

Condition or disease Intervention/treatment Phase
Overweight Obesity Insulin Resistance Other: Plant-based diet Other: Control Diet Not Applicable

Detailed Description:

In a 16-week trial, overweight adults will be randomly assigned to two groups. Changes in beta-cell function will be the primary outcome. Changes in insulin sensitivity will be the secondary outcome. Changes in postprandial metabolism, and body weight will be the tertiary outcomes.

The Diet Group will be asked to follow a low-fat, vegan diet and will receive weekly classes and support.

The Control Group will be asked to follow a conventional control diet..

This study conducts a pilot substudy to test the hypothesis that changes in insulin sensitivity and beta-cell function observed in response to a diet intervention correlate with changes in intramyocellular and/or intrahepatocellular lipid. Another sub-study assesses the association between metabolic outcomes and gut microbiome. One additional sub-study is looking for associations between metabolic outcomes and endothelial function.


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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 220 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: A Randomized, Controlled Trial on Diet, Insulin Sensitivity, and Postprandial Metabolism
Actual Study Start Date : October 2016
Actual Primary Completion Date : December 2018
Actual Study Completion Date : January 9, 2019

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Allergy
Drug Information available for: Insulin

Arm Intervention/treatment
Active Comparator: Plant-based diet
The diet group will be asked to follow a low-fat, vegan diet for 16 weeks
Other: Plant-based diet
Weekly instructions will be given to the participants in the intervention group about following vegan diet.
Other Name: Vegan diet

Active Comparator: Control diet
Half of the participants will be asked to continue their usual diets for the 16-week study period.
Other: Control Diet
Participants will be asked to continue their usual diets for the 16-week study period.




Primary Outcome Measures :
  1. Beta-cell function [ Time Frame: 16 weeks ]
    A 3-hour standard meal test will be performed after an overnight fast. Glucose, insulin and C-peptide will be measured at 0, 30, 60, 120, and 180 min.

  2. Insulin resistance [ Time Frame: 16 weeks ]
    Insulin resistance will be assessed by the HOMA index.


Secondary Outcome Measures :
  1. Resting Energy Expenditure (REE) and postprandial metabolism [ Time Frame: 16 weeks ]

    Participants will be asked to report to the laboratory within 60 minutes of waking and after a 12-hour fast. Following 30 minutes of quiet rest in a dimly lit room, pulse, respiratory rate, and body temperature will be measured. REE will be measured for 20 minutes through indirect calorimetry (Cosmed Quark RMR, Chicago, IL) utilizing a ventilated hood system. The laboratory temperature will be maintained at 23 degrees C throughout, and precautions will be taken to minimize any disturbances that could affect the metabolic rate.

    For premenopausal women, measures will be timed so as to occur in the luteal phase of the menstrual cycle. Postprandial metabolism will be measured for three hours after the standard meal.


  2. Body weight [ Time Frame: 16 weeks ]
    Anticipated weight-loss for intervention group compared with control group.

  3. Changes in intramyocellular and/or intrahepatocellular lipid [ Time Frame: 16 weeks ]
    A subset of participants will be selected for MR spectroscopy studies quantifying hepatic lipid and/or intramyocellular and/or contents in order to provide data regarding possible causal relationships between dietary changes, ectopic lipid, and insulin sensitivity. Selected individuals with varying degrees of insulin-resistance in both groups will be assessed before and after the intervention period. These MRS studies will take place at the Magnetic Research Center at Yale University School of Medicine, New Haven, CT.

  4. Microbiome Analysis [ Time Frame: 16 weeks ]
    Microbiome analysis from participant-provided stool sample. Analysis from uBiome in a subset of participants. Anticipated changes in the dietary intervention group include changes in the microbiome composition that correlate with changes in insulin sensitivity.

  5. Endothelial function [ Time Frame: 16 weeks ]
    Endothelial function will be measured using the EndoPAT in a subset of participants.

  6. Diet Assessment Recall Questionnaire [ Time Frame: 16 weeks ]
    24-hour multi-pass dietary recalls will be used to assess dietary adherence to assist study personnel in working with individuals who need additional teaching or support.

  7. The Effect of Fat Quantity & Quality on Body Composition, Insulin Resistance, & Insulin Secretion [ Time Frame: 16 Weeks ]
    Regression Analysis will be used to assess The Effect of Fat Quantity & Quality on Body Composition, Insulin Resistance, & Insulin Secretion

  8. The Effect of Carbohydrate Quantity & Quality on Body Composition & Insulin Resistance [ Time Frame: 16 Weeks ]
    Regression Analysis will be used to assess The Effect of Carbohydrate Quantity & Quality on Body Composition & Insulin Resistance

  9. The Effect of Protein Quantity & Quality on Body Composition, Insulin Resistance, & Insulin Secretion [ Time Frame: 16 Weeks ]
    Regression Analysis will be used to assess The Effect of Protein Quantity & Quality on Body Composition, Insulin Resistance, & Insulin Secretion

  10. Levels of Advanced Glycosylation Endproducts (AGEs) [ Time Frame: 16 Weeks ]
    An AGE reader will be used to measure the Levels of the AGEs in the skin



Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • Men and women age ≥18 years of age
  • Body mass index 28-40 kg/m2

Exclusion Criteria:

  1. Diabetes mellitus, type 1 or 2, history of diabetes mellitus or of any endocrine condition that would affect body weight, such as thyroid disease, pituitary abnormality, or Cushing's syndrome
  2. Smoking during the past six months
  3. Alcohol consumption of more than 2 drinks per day or the equivalent, episodic increased drinking (e.g., more than 2 drinks per day on weekends), or a history of alcohol abuse or dependency followed by any current use
  4. Use of recreational drugs in the past 6 months
  5. Use within the preceding six months of medications that affect appetite or body weight, such as estrogens or other hormones, thyroid medications, systemic steroids, antidepressants (tricyclics, MAOIs, SSRIs), antipsychotics, lithium, anticonvulsants, appetite suppressants or other weight-loss drugs, herbs for weight loss or mood, St. John's wort, ephedra, beta blockers
  6. Pregnancy or intention to become pregnant during the study period
  7. Unstable medical or psychiatric illness
  8. Evidence of an eating disorder
  9. Likely to be disruptive in group sessions
  10. Already following a low-fat, vegan diet
  11. Lack of English fluency
  12. Inability to maintain current medication regimen
  13. Inability or unwillingness to participate in all components of the study
  14. Intention to follow another weight-loss method during the trial

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02939638


Locations
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United States, District of Columbia
Physicians Committee for Responsible Medicine
Washington, District of Columbia, United States, 20016
Sponsors and Collaborators
Physicians Committee for Responsible Medicine
Yale University
Investigators
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Principal Investigator: Neal D Barnard, M.D. President

Publications:

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Responsible Party: Physicians Committee for Responsible Medicine
ClinicalTrials.gov Identifier: NCT02939638     History of Changes
Other Study ID Numbers: Pro00018983
First Posted: October 20, 2016    Key Record Dates
Last Update Posted: March 20, 2019
Last Verified: March 2019
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Undecided

Keywords provided by Physicians Committee for Responsible Medicine:
Plant-based diet
Obesity
Insulin sensitivity
Intracellular lipid
Postprandial metabolism
Vegan diet
Beta-cell function

Additional relevant MeSH terms:
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Insulin Resistance
Hypersensitivity
Overweight
Body Weight
Signs and Symptoms
Immune System Diseases
Hyperinsulinism
Glucose Metabolism Disorders
Metabolic Diseases
Insulin
Hypoglycemic Agents
Physiological Effects of Drugs