Introduction: Lifestyle interventions aiming to reduce excess body weight have been focusing on individuals living with overweight or obesity. However, many health-related behaviors including eating are concordant in couples indicating they might share an obesity risk or support each other's weight loss efforts. Aim: The aim of this systematic review and meta-analysis of randomized controlled trials was to assess the weight change effects of lifestyle interventions targeting couples in a romantic relationship regardless of marital status or sexual preference compared to individuals or no intervention. Methods: Four databases (MEDLINE Ovid, Scopus, CINHAL, and mySearch: EBSCO-Discovery-Service-Tool) were systematically searched from inception until 26th April 2021 with further email alerts. The risk of bias was assessed using the Critical Appraisal Skills Programme. Meta-analysis was conducted using the random-effect model to estimate the weighted mean difference with 95% confidence interval. Results: Seventeen studies were eligible for this review and 11 of them were included in the meta-analysis for weight change. Significant intervention effects were identified for body weight in couples’ intervention vs. individual intervention (−2.25 kg, 95% CI−3.63 to−0.88), and vs. no intervention (−4.5 kg, 95% CI−6.62 to−2.38). Conclusion: This systematic review and meta-analysis was the first to investigate the effectiveness of lifestyle interventions targeting couples on weight loss, compared to interventions focused on individuals or standard care. The findings suggest that interventions aimed at couples lead to greater weight loss, though the results should be interpreted with caution due to the wide heterogeneity among the studies. Further research is needed with evidence-based study designs, targeting younger participants, and incorporating longer intervention durations and follow-up periods.
