The Feasibility and Acceptability of a Pragmatic Food-Based Very-Low-Energy Intervention in Adults with Obesity: A Pilot Single-Arm Intervention Study

Background/Objectives: The objective of this study was to evaluate the feasibility, acceptability, weight loss response, safety and preliminary clinical outcomes of a pragmatic 8-week food-based very-low-energy intervention in adults with obesity. Methods: In this prospective, single-arm study, 10 adults eligible for very-low-energy diet (VLED) therapy completed an 8-week food-based intervention targeting approximately 800 kcal/day with an accepted intake range up to 1000 kcal/day. Participants planned, purchased and prepared all foods, supported by dietary self-monitoring and fortnightly dietitian consultations. The primary feasibility outcomes were acceptability and weight loss response. The secondary outcomes included recruitment, retention and engagement. The exploratory outcomes included anthropometric measures, blood pressure, nutritional and biochemical markers, dietary quality, nutritional adequacy and adverse events. Results: All participants completed the intervention. Nine of 10 (90%) Food Acceptability Questionnaire (FAQ) scores met their prespecified item-level acceptability thresholds, while 90% (95%CI 55.5 to 99.7%) of participants achieved ≥5% weight loss. Mean weight loss was 10.8%. Attendance at study visits was 100% (95% CI 69.2 to 100%). Participants completed 93 ± 13% of expected food diary days with mean daily energy intakes of 842 ± 70 kcal/day. Statistically significant improvements were observed in anthropometric measures, blood pressure, total and LDL cholesterol and dietary quality. No clinically concerning changes in micronutrient or safety parameters were observed. Adverse events were predominantly mild to moderate. Conclusions: This pragmatic 8-week food-based very-low-energy intervention demonstrated encouraging feasibility outcomes, although challenges associated with eating out warrant further attention. Further evaluation in larger controlled trials is needed to assess its comparative effectiveness relative to traditional meal replacement VLEDs and longer-term outcomes.