White kidney bean extract reduces body weight and adiposity with acceptable safety in adults with overweight and obese: a systematic review and meta-analysis

Abstract

The global prevalence of overweight and obesity has risen sharply in recent decades, becoming a major public health concern. White kidney bean (Phaseolus vulgaris L.) extract (WKBE), rich in α-amylase inhibitors, may delay carbohydrate digestion and reduce energy intake. We hypothesized that WKBE could significantly improve key anthropometric outcomes in adults with overweight and obese compared with placebo, with acceptable safety. To test this hypothesis, we systematically searched four databases from inception to January 31, 2026, for randomized controlled trials of oral WKBE. Eight randomized controlled trials (n = 543) met the inclusion criteria. Random-effects meta-analyses showed reductions in weight (MD -1.62 kg, 95% confidence interval [CI] -1.99 to -1.25), body mass index (MD -0.58 kg/m², 95% CI -0.73 to -0.43), fat mass (MD -1.17 kg, 95% CI -1.80 to -0.55), waist (MD -1.58 cm, 95% CI -2.19 to -0.96), and hip (MD -0.99 cm, 95% CI -1.94 to -0.05) (all P < .05). No significant differences were observed in fasting blood glucose, triglycerides, or random insulin. No serious adverse events related to WKBE were reported. These findings indicate that WKBE may serve as a generally well-tolerated, nonpharmacological adjunct for weight management. In the future, further large-scale, high-quality, and long-term trials are warranted to confirm its efficacy and clarify its potential role in metabolic health.

Keywords: Body composition; Obesity; Overweight; Phaseolus vulgaris extract; Randomized controlled trial; Weight management; White kidney bean extract; α-amylase inhibitor.