Remotely Delivered Behavioral Weight Loss Using an Ad Libitum Plant-Based Diet Versus a Balanced Calorie Deficit Diet

Study Overview
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Brief Summary
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This pilot randomized controlled trial will compare a remotely delivered behavioral weight loss program with a balanced calorie deficit diet (the current gold-standard) to a behavioral weight loss program with an ad libitum whole food plant-based diet (WFPBD) amongst adults with overweight/obesity (N = 52). The 6-month intervention will consist of 3 months of moderate-intensity intervention (weekly online modules and brief coaching calls), then a low-intensity period (3 calls over 3-months). Assessments will occur at baseline, 6-weeks, 12-weeks, and post-treatment (6-months). Acceptability, dietary adherence, weight, quality of life, depressive symptoms, and subjective appetite will be assessed.

Official Title
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Evaluating a Remotely Delivered Behavioral Weight Loss Intervention Using an Ad Libitum Plant-Based Diet Versus a Balanced Calorie Deficit Diet

Conditions
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Obesity, Overweight

Intervention / Treatment
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* Behavioral: Lifestyle Modification Intervention
* Behavioral: Balanced Calorie Deficit Eating Plan
* Behavioral: Ad Libitum Whole Food Plant-Based Eating Plan


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: BMI 27-50 kg/m2 Ages 18-75 years Resides in the U.S. Consistent access to internet at home Proficient skill level in speaking, writing, and understanding English Reporting a desire to lose weight Consistently available for 15-minute once-weekly video appointment between the hours of 8 AM and 7 PM EST Willing to follow a whole food plant-based diet or a traditional calorie-reduced diet for the study duration Individuals must provide consent for the research team to contact their personal physician if necessary, to provide clearance or to consult about rapid weight loss Exclusion Criteria: Currently pregnant or breastfeeding or planned pregnancy within the study period Recent weight loss (≥ 5% weight loss in 3-months prior to the study) History of bariatric surgery Currently following a low-fat plant-based diet Medical condition (e.g., cancer, type I diabetes, renal failure), current substance use problem, or psychiatric condition (e.g., active substance abuse, eating disorder) that may pose a risk to the participant during intervention or cause a change in weight Recently began or changed the dose of a medication that can cause significant change in weight Planning on quitting cigarette smoking over the program period Participation in a concurrent weight loss program during the study period Medical diagnosis currently influencing weight or appetite Medical condition that would limit ability to participate in this program (for example, mild stroke, diabetes if taking insulin, head trauma, cognitive disorder) Acute suicidality Currently meets criteria for regular loss-of-control eating (i.e., ≥ 9 binge episodes in past 3 months Currently reports engaging in a compensatory behavior

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Lifestyle Modification with a Balanced Calorie Deficit Diet<br>Lifestyle modification intervention with a balanced calorie deficit diet (i.e., participants will be prescribed a calorie goal and will track their dietary intake in order to meet this goal). | Behavioral: Lifestyle Modification Intervention<br>* For the first 12-weeks of the study, participants will complete weekly web modules in which they will learn cognitive-behavioral strategies to support lifestyle modification. Participants will also receive weekly phone coaching calls for the first 12-weeks of the study, and monthly coaching calls thereafter for the remainder of the 24-week study period.<br>Behavioral: Balanced Calorie Deficit Eating Plan<br>* Participants will be prescribed a calorie target between 1200 and 1800 depending upon baseline weight and personal preference. Participants will be asked to monitor their dietary intake using MyFitnessPal and to submit food logs weekly. Calorie reduction content will be based primarily on the Diabetes Prevention Program protocol and adapted from existing behavioral treatment protocols. Individuals will receive general guidelines on eating a healthy diet, including reducing saturated fat, processed foods, refined sugars, and refined carbohydrates, and increasing intake of lean proteins, whole grains, and fruits and vegetables, but will be encouraged to flexibly decide which areas of their diet to modify to reduce calorie intake.<br>|
| Experimental: Lifestyle Modification with an Ad Libitum Whole Food Plant-Based Eating Plan<br>Lifestyle modification intervention with an ad libitum whole food plant-based diet (i.e., participants will eat, ad libitum, fruits, vegetables, starches, legumes, and whole grains, and will avoid eating processed foods, refined oils, and animal products) | Behavioral: Lifestyle Modification Intervention<br>* For the first 12-weeks of the study, participants will complete weekly web modules in which they will learn cognitive-behavioral strategies to support lifestyle modification. Participants will also receive weekly phone coaching calls for the first 12-weeks of the study, and monthly coaching calls thereafter for the remainder of the 24-week study period.<br>Behavioral: Ad Libitum Whole Food Plant-Based Eating Plan<br>* Participants will be prescribed a whole food plant-based (WFPB) low-fat vegan diet promoting intake of fruits, vegetables, starches, legumes, and whole grains. Participants will be encouraged to avoid processed foods, refined oils, and animal products (meat, fish, eggs, and dairy products), and to minimize consumption of high-fat plant-based foods. An adapted traffic-light diet chart will outline foods to eat daily, limit, and avoid. Participants will be advised to eat until satiation and not restrict energy intake. Participants will be asked to consume 50 μg vitamin B12 (methylcobalamin) daily. WFPB nutrition counseling content will be based upon existing successful programs. Each week, participants will complete a simplified dietary self-monitoring food frequency questionnaire aligned to correspond with the traffic light diet chart.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Weight Change | Weight loss will be self-reported by participants using a standardized weighing procedure. Participants will weigh themselves in lightweight clothes without shoes with a digital scale accurate to 0.1 kg. Percent weight loss at 6-months will be calculated as the percentage loss in initial body weight at baseline by the time of the post-treatment assessment. | Measured at each assessment baseline, mid-treatment (6- and 12-weeks) and post-treatment (6-months). | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Subjective Appetite as assessed by visual analogue scale (VAS) | Subjective appetite will be assessed using 6 visual analogue scale items (VAS) inquiring about past-week hunger, fullness, the degree to which hunger made it difficult to follow the prescribed diet, preoccupation with thoughts of food, and being bothered by hunger on a visual analogue scale of 0-100. Scores on the fullness item will be reversed, such that higher scores will indicate greater subjective appetite. | Measured at baseline, mid-treatment (6- and 12-weeks) and post-treatment (6-months). | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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vegetarian, behavioral weight loss, weight loss, dietary self-monitoring, obesity