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Completed

NCT Number: NCT03698955

Low-Fat Vegan Diet Versus a Mediterranean Diet on Body Weight

This randomized, cross-over trial aims to assess changes in body weight, plasma lipids, insulin sensitivity, and postprandial metabolism with a low-fat, plant-based diet and a Mediterranean diet, both followed for 4 months.

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Key information

Conditions

Overweight Body Weight Glucose Metabolism Disorders Hyperinsulinism Insulin Resistance Metabolic Diseases Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Physicians Committee for Responsible Medicine

Washington D.C., District of Columbia, 20016, United States

About this study

In a 36-week cross-over trial, overweight adults will consume a low-fat vegan diet and a Mediterranean diet in two separate 16-week phases. Changes in body weight will be the primary dependent variable. In addition, plasma lipid concentrations, insulin sensitivity, and postprandial metabolism will also be assessed and changes over time will be compared between the two diets.

Participants will be randomly assigned to start either a low-fat vegan diet or a Mediterranean diet for 16 weeks. Both groups will receive weekly classes and support, and will be asked to make no changes to their exercise patterns for the study period. After a 4-week washout period, participants will cross over to the second dietary intervention for another 16 weeks.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

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

Exclusion criteria

  • Diabetes mellitus type 1, history of any endocrine condition that would affect body weight, such as thyroid disease, pituitary abnormality, or Cushing's syndrome
  • Smoking during the past six months
  • 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
  • Use of recreational drugs in the past 6 months
  • Use within the preceding six months of medications that affect appetite or body weight, such as estrogens or other hormones, thyroid medications (unstable dose within the preceding 6 months), 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
  • Pregnancy or intention to become pregnant during the study period, as verified by self--- - Unstable medical or psychiatric illness
  • Evidence of an eating disorder
  • Likely to be disruptive in group sessions
  • Already following a low-fat vegan diet or Mediterranean diet
  • Lack of English fluency
  • Inability to maintain current medication regimen
  • Inability or unwillingness to participate in all components of the study
  • Intention to follow another weight-loss method during the trial

Treatment and study plan

Plant-Based Diet

Other

Weekly instructions will be given to the participants in the intervention group about following the vegan diet.

Other names: Vegan diet

Mediterranean Diet

Other

Weekly instructions will be given to the participants in the intervention group about following the Mediterranean diet.

Primary outcomes

  1. Body weight

    Time frame: Change in body weight from Baseline at 4 months

    Body weight will be assessed at the baseline and at the completion of both interventions.

  2. Plasma lipids

    Time frame: Change in plasma cholesterol, triglycerides, and HbA1c from Baseline at 4 months

    Plasma cholesterol, triglycerides, and HbA1c will be measured in a fasting state.

  3. Insulin sensitivity

    Time frame: Change in insulin sensitivity from Baseline at 4 months

    Insulin sensitivity will be assessed by the HOMA index.

  4. Metabolism

    Time frame: Changes in metabolism from Baseline at 4 months

    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.

Secondary outcomes

  1. Levels of Advanced Glycosylation Endproducts (AGEs)

    Time frame: Change in Advanced Glycosylation Endproducts (AGEs) from Baseline at 4 months

    An AGE reader will be used to measure the Levels of the AGEs in the skin

  2. Endothelial function

    Time frame: Change in Endothelial function from Baseline at 4 months

    Endothelial function will be measured using the EndoPAT.

  3. Microbiome analysis

    Time frame: Change in Microbiome from Baseline at 4 months

    Microbiome analysis will be performed from participant-provided stool sample. Anticipated changes in the dietary intervention group include changes in the microbiome composition that correlate with changes in insulin sensitivity.

  4. Dietary Advanced Glycation End Products (AGEs)

    Time frame: 16 weeks

    Explore the effectiveness of a vegan diet in reducing dietary AGEs.

  5. PDI, hPDI, uPDI

    Time frame: 16 weeks

    Assess the total plant-based index (PDI), healthy PDI, and unhealthy PDI, and their relationship with weight loss.

  6. Ultraprocessed foods

    Time frame: 16 weeks

    The consumption of ultraprocessed foods will be assessed, using the NOVA classification, at baseline and 16 weeks.

  7. Carbon Footprint

    Time frame: 16 weeks

    The greenhouse gas emissions (GHGE) and cumulative energy demand (CED) will be assessed, using the database of Food Impacts on the Environment for Linking to Diets (dataFIELD) and What We Eat In America (WWEIA) database, at baseline and 16 weeks.

  8. Food costs

    Time frame: 16 weeks

    Food costs will be assessed, using the U.S. Department of Agriculture Thrifty Food Plan, 2021, at baseline and 16 weeks.

Sponsors and collaborators

Lead sponsor

Physicians Committee for Responsible Medicine

Other

Registry information

Official study title

A Randomized, Cross-Over Trial on the Effects of a Low-Fat Vegan Diet Versus a Mediterranean Diet on Body Weight

Important dates

Study start
2018
Primary completion
2019
Study completion
2019
First posted
Oct 9, 2018
Registry last updated
Sep 27, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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