Trajectories and predictors of psychological distress during the first 6 months of weight loss among adults with obesity: a prospective longitudinal cohort study

Objectives To characterize longitudinal trajectories of psychological distress from first presentation to a weight management clinic through 6 months of weight loss. Methods Adults with obesity (body mass index, BMI ≥28 kg/m²) were consecutively recruited from October 2024 to May 2025. Psychological distress was evaluated at four time points: initial clinic presentation (T1), 1 month (T2), 3 months (T3), and 6 months (T4) after weight loss initiation. Latent class growth modeling (LCGM) was applied to identify heterogeneous psychological distress trajectories. Multinomial logistic regression was used to explore baseline predictors for trajectory membership, with the persistently no/low distress group as the reference group (C3). Results LCGM identified three distinct longitudinal trajectories of psychological distress: Trajectory 1 (C1, 63.7%): gradually decreasing distress over 6 month s; Trajectory 2 (C2, 21.1%): continuously increasing distress; Trajectory 3 (C3, 15.2%): persistently no or low-level distress. Multinomial regression results showed that C1 membership was independently associated with younger age (OR=0.858, 95%CI: 0.745 to 0.988), history of chronic disease (OR = 1.293, 95%CI: 1.018 to 1.642), higher negative coping (OR = 1.445, 95%CI: 1.166 to 1.791), lower perceived social support (OR = 0.912, 95%CI: 0.832 to 1.000), and more negative illness perception (OR = 1.064, 95%CI: 1.002 to 1.163). C2 membership was independently associated with younger age (OR = 0.827, 95%CI: 0.760 to 0. 988), female sex (male vs female OR = 0.131, 95%CI: 0.024 to 0.708), higher BMI (OR = 1.337, 95%CI: 1.055 to 1.695), higher negative coping (OR = 1.319, 9 5%CI: 1.043 to 1.667), lower perceived social support (OR = 0.867, 95%CI:0.79–3 to 0.947), and more negative illness perception (OR = 1.080,95%CI:1.002 to 1.164). Conclusions Psychological distress among obese adults during early weight loss presents obvious heterogeneity. Nearly one-fifth of patients experience progressive elevation in distress, which requires close clinical attention. Routine assessment of baseline psychosocial and clinical indicators can support early risk stratification and facilitate delivery of timely psychological and behavioral interventions within the first 6 months of weight loss.