Effectiveness of specialist-delivered interventions in severe mental illness: A systematic review and meta-analysis

Objective: To establish the effectiveness of specialist-delivered nutrition and exercise interventions on the physical health of people with severe mental illness. Methods: An electronic database search was completed from earliest record to August 2024 using Scopus, Medline, EMBASE, PsycINFO, and CINAHL, using key nutritional, cardiometabolic and psychiatric terminology. Eligible studies were randomised and non-randomised controlled trials which included specialist-delivered interventions (dietitian and/or nutritionist or exercise professional) with people diagnosed with severe mental illness. Primary outcomes were cardiometabolic risk factors. Results: Thirty-one studies were included: combined nutrition and exercise intervention ( n = 12), nutrition intervention only ( n = 9), and exercise intervention only ( n = 10), with 23 contributing to the meta-analysis. Meta-analysis of combined nutrition and exercise interventions revealed positive-effects on body mass index (BMI) (Mean diff = −1.78 [95% confidence interval (CI) −2.97 to −0.59], p = 0.00) and waist circumference (Mean diff = −4.13 [95% CI −7.25 to −1.00] p = 0.01). In nutrition-only intervention studies, the meta-analysis revealed a positive-effect on systolic blood pressure (Mean diff = −6.14 [95% CI −12.02 to −0.26] p = 0.04). No significant impacts were tested for exercise-only interventions. Conclusion: Specialist-delivered nutrition and exercise interventions are effective in improving weight, BMI and waist circumference status over the short to medium term in people diagnosed with severe mental illness. Exercise and nutrition programmes show promising effectiveness, and this research provides evidence to support the implementation as part of standard care of people diagnosed with severe mental illness.