Clinical trial NCT02939638: Diet, Insulin Sensitivity, and Postprandial Metabolism
Official title: A Randomized, Controlled Trial on Diet, Insulin Sensitivity, and Postprandial Metabolism
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Overweight
Obesity
Insulin Resistance
Keywords: Plant-based diet
Obesity
Insulin sensitivity
Intracellular lipid
Postprandial metabolism
Vegan diet
Beta-cell function
Lead sponsor: Physicians Committee for Responsible Medicine
Sponsor class: OTHER
Collaborators: name: Yale University
First posted: 2016-10-20
Enrollment: 220
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

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 body weight, body composition, intramyocellular and/or intrahepatocellular lipid, and changes in association to body weight.

Detailed description: In a 16-week trial, overweight adults will be randomly assigned to two groups. Changes in body weight, body composition, intramyocellular and/or intrahepatocellular lipid, and changes in association to body weight will be measured among other outcomes.

The Intervention Group will 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 sub-study 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.

Eligibility 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, monoamine oxidase inhibitors (MAOIs), selective serotonin reuptake inhibitors (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

Primary outcomes:
measure: Body weight in kg
timeFrame: 16 weeks
measure: Fat mass in grams
timeFrame: 16 weeks
measure: Visceral fat in cm^3
timeFrame: 16 weeks
measure: Changes in intramyocellular and/or intrahepatocellular lipid
timeFrame: 16 Weeks
measure: Insulin resistance
timeFrame: 16 weeks
measure: Resting Energy Expenditure (REE)
timeFrame: 16 weeks
measure: Postprandial metabolism
timeFrame: 16 weeks
Secondary outcomes:
measure: Beta-cell function as measured by glucose (mmmol/L)
timeFrame: 16 weeks
measure: Beta-cell function as measured by insulin (pmol/L)
timeFrame: 16 weeks
measure: Beta-cell function as measured by C-peptide (ng/mL)
timeFrame: 16 weeks
measure: Microbiome Analysis
timeFrame: 16 weeks
measure: Endothelial function
timeFrame: 16 weeks
measure: Diet Assessment Recall Questionnaire
timeFrame: 16 weeks
measure: The Effect of Fat Quantity & Quality on Body Composition, Insulin Resistance, & Insulin Secretion
timeFrame: 16 Weeks
measure: The Effect of Carbohydrate Quantity & Quality on Body Composition & Insulin Resistance
timeFrame: 16 Weeks
measure: The Effect of Protein Quantity & Quality on Body Composition, Insulin Resistance, & Insulin Secretion
timeFrame: 16 Weeks
measure: Levels of Advanced Glycosylation Endproducts (AGEs)
timeFrame: 16 Weeks
measure: Race Disparities
timeFrame: 16 weeks
measure: Dietary Advanced Glycation End Products (AGEs)
timeFrame: 16 weeks
measure: Food costs
timeFrame: 16 weeks
measure: PDI, hPDI, uPDI
timeFrame: 16 weeks
measure: Ultraprocessed foods
timeFrame: 16 weeks
Other outcomes:
Locations:
city: Washington
country: United States
facility: Physicians Committee for Responsible Medicine
state: District of Columbia
Study officials:
affiliation: President
name: Neal D Barnard, M.D.
role: PRINCIPAL_INVESTIGATOR
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