Evaluating a Remotely Delivered Plant-Based Behavioral Weight Loss Treatment

A Pilot Study of a Novel Ad Libitum Plant-Based Behavioral Weight Loss Treatment

Many individuals do not achieve clinically significant weight loss following traditional lifestyle modification interventions, potentially because weight loss is dependent upon calorie tracking compliance (to achieve calorie prescriptions), which decreases over time for most. By contrast, non-energy-restricted whole food plant-based diets (WFPBD) have been demonstrated to promote clinically significant weight loss even without calorie prescriptions. The present pilot trial represents the first, to the knowledge of our study team, to empirically test a remotely delivered WFPBD behavioral weight loss intervention for adults with overweight or obesity. Over 12-weeks, participants (N = 21) will follow a non-energy-restricted WFPBD and received nutritional counseling and behavioral weight loss intervention. Participation will occur in two phases (Phase 1: n = 7; Phase 2: n = 14), between which iterative changes to the intervention will be made. Assessments will occur at baseline, mid-treatment, post-treatment, and 3-month follow-up. Data will be analyzed using an intent-to-treat approach. The primary aims of the study will be to assess retention feasibility and acceptability. The secondary aims will be to evaluate the preliminary effectiveness of the intervention on: (1) percent weight loss; (2) dietary intake (i.e., increased intake of low-fat plant-based whole foods and decreased in intake of processed foods and animal products); and (3) waist circumference. The exploratory aims will be to evaluate the preliminary effectiveness of the intervention on physical- and mental health-related quality of life, and to examine potential moderators of treatment success (plant-based diet history, internal disinhibition, social support vs. social sabotage, self-compassion, and psychological flexibility).

Inclusion Criteria:

• Aged 18-75
• Current BMI ≥ 25 kg/m2
• Reporting a desire to lose weight
• Have at-home internet access
• Proficiency in speaking, reading, and writing English
• Willing to consume a whole foods plant-based diet for the study duration

Exclusion Criteria:

• Use of medications for weight loss
• Recent weight loss (≥5% weight loss in prior 3-months)
• Current or planned pregnancy within the study period
• History of bariatric surgery
• Currently following a low-fat plant-based diet
• Diagnosis of a serious medical condition influencing weight, appetite, or eating behavior
• Diagnosis of a serious psychiatric condition that may influence weight, appetite, or eating behavior
• Current substance use disorder
• Participation in a concurrent weight loss program
• Planning on quitting smoking over the intervention period (if current smoker)
• Eating pathology (lifetime history of an eating disorder, ≥ 9 binge eating episodes in the past 3 months, or > 5 compensatory episodes in the past 3 months)