Effects of Plant-Based Diets on Weight Status in Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Excessive adiposity is a major risk factor for type 2 diabetes (T2D), and dietary patterns are important determinants of weight status. Plant-based dietary patterns (PBDs) are known for their therapeutic effects on T2D. The aim is to systematically review RCTs to investigate the effects of various PBDs compared to regular meat-eating diets (RMDs), in individuals who normally consume a RMD on body weight, BMI, and waist circumference in T2D. RCTs investigating PBDs and body weight, BMI, WC for ≥6 weeks in adults with T2D since 1980 were eligible for inclusion. Seven trials ( = 269) were included in the meta-analysis using random-effects models and expressed as MD (95%Cls). Compared to RMDs, PBDs significantly lowered body weight (-2.35 kg, 95% CI: -3.51, -1.19, < 0.001), BMI (-0.90 kg/m, 95% CI: -1.42, -0.38, = 0.001) and WC (-2.41 cm, 95% CI: -3.72, -1.09, < 0.001). PBDs alone significantly reduced body weight by 5.1% (-4.95 kg, 95% CI: -7.34, -2.55, < 0.001), BMI by 5.4% (-1.87 kg/m, 95% CI: -2.78, -0.95, < 0.001) and WC by 4.3%(-4.23, 95% CI: -6.38, -2.07, < 0.001). Interventions not limiting energy intake led to a significant reduction in body weight (-2.54 kg, 95% CI: -4.16, -0.92, < 0.005) and BMI (-0.91 kg/m, 95% CI: -1.56, -0.25, < 0.005). Trials ≥16 weeks had a pronounced reduction in body weight (-2.93 kg, 95% CI: -5.00, -0.87, = 0.005) and BMI (-1.13 kg/m, 95% CI: -1.89, -0.38, < 0.005). These findings provide evidence for the implementation of PBDs for better management of central adiposity in individuals with T2D.