Persisting unhealthy eating behaviors and the role of dieting in outpatients treated for severe mental illness: Findings from a longitudinal study

Individuals living with severe mental illness (SMI) are at higher risk of being overweight and obese. In addition to medication side effects, poor dietary habits are considered as modifiable factors. However, individuals with SMI face a variety of barriers to healthy eating, and it is still unclear which dietary strategies are best. The current study aimed to examine the course of dietary habits in dieting and non-dieting patients treated at a psychiatric day clinic. In this longitudinal observational study, symptom severity, dietary habits, and other health-risk behaviors of = 53 psychiatric outpatients with a primary ICD-10 diagnosis (85% F3 and 15% F2) were assessed at the start of treatment in a psychiatric day clinic and after 3 months using semi-structured interview data and anthropometric measurements. Patients' mental health improved after 3 months of treatment (e.g. lower scores on a modified Global Assessment of Functioning Scale (m-GAF) and on the 9-item Patient Health Questionnaire (PHQ-D)). However, BMI and lifestyle behaviors (e.g. diet quality, physical activity, and smoking) remained unchanged. Fewer depressive symptoms and dieting were even associated with weight gain over the 3 months (+1.7 kg). Compared with non-dieters, dieters had higher levels of neuroticism and ambivalence about eating, were more likely to overeat and were more dissatisfied with their body weight. The group of dieters may benefit from professional support to achieve a healthier lifestyle.