Process Evaluation of a Time-Restricted Eating Intervention for Weight Management in South African Women Living with Overweight/Obesity and HIV on Dolutegravir-Based Antiretroviral Therapy: A Qualitative, RE-AIM-Informed Analysis

Background: South Africa faces the world's highest HIV burden, disproportionately affecting women, alongside rising Type 2 Diabetes (T2D). Weight gain associated with preferred dolutegravir (DTG)-based antiretroviral therapy may worsen obesity and T2D risk. This process evaluation explored the implementation of a 12-month time-restricted eating (TRE) intervention for weight management in women with HIV and overweight/obesity in Khayelitsha, Cape Town. Methods: Using the RE-AIM framework, the study investigated the implementation journey. Data were collected from three groups: RCT participants, healthcare workers (n = 21), and fieldworkers (n = 3). Methods included structured informal interviews with TRE participants throughout the intervention and semi-structured in-depth interviews (IDIs) with a subset (n = 19) at 12 months. IDIs and focus group discussions were conducted with healthcare staff. Results: Implementation faced significant contextual challenges, including high food insecurity, economic constraints, and high crime levels. Cultural norms around food hospitality also posed barriers. Despite this, TRE was highly feasible and acceptable. Participants reported positive behavioural changes, establishing eating routines and consuming healthier foods. Perceived health benefits included improved appetite control, wellbeing, sleep, and weight management. Key facilitators were the intervention's flexibility and, importantly, the non-judgmental, empathetic support from fieldworkers, which drove engagement and retention. Healthcare workers expressed willingness to integrate TRE into existing HIV counsellor-led services, and nearly all participants desired to continue TRE post-intervention. Conclusions: This process evaluation demonstrates that TRE is a contextually suitable and acceptable intervention from an implementation perspective. Its success in practice, however, depends on mitigating complex multi-level barriers through a flexible program design and high-quality, relationship-focused support integrated into existing healthcare infrastructure. Trial registration: PACTR202302484999720, 8 February 2023.