Plain language summary
With obesity on the rise this analysis of 22 trials and a total of 870 overweight or obese adults looks at whether soy products are effective food for weight loss. Sixteen trials examined soy products and Body Mass Index (BMI) and concluded that soy products significantly reduced body mass compared to the control groups. The remaining studies examined the effects of soy on fat mass, fat percentage, and waist and hip circumference and showed declines in fat mass but not significant reductions in waist and hip measurements. The amalgamated results showed a total reduction of 0.34 kg body weight. Various types of soy products were included such as soy protein, isoflavones, soy milk, soy shakes and some other soy products. Further sub-group analysis showed differences in people from developed countries (typically a BMI higher than 25.0) versus developing countries (average BMI lower than 25.0). They also highlighted differences between cultures with meat-based and plant-based diets and the wide acceptance of soy in Asia. Significant effects were observed in non-menopausal women with reduced body weight, BMI and waist circumference, while no results were observed in postmenopausal women. The study concludes that soy protein, isoflavones and fibre all contribute to fullness and signalling pathways which may be helpful in reducing body weight.
Abstract
BACKGROUND The effect of soy products on the weight of overweight or obese people is controversial, so we aimed to conduct a systematic review and a meta-analysis of published randomized controlled trials to analyze whether supplementation with soy products can help them to lose weight. METHODS The relevant data before January 2019 in PubMed, Embase and Cochrane Library were searched. A random-effect model was adopted to calculate the weighted average difference of net changes of body weight, body mass index (BMI), body fat percentage, fat mass, waist circumference, etc. Results: A total of 22 trials (870 overweight or obese participants) were reflected in the present meta-analysis. Analysis showed that soy products significantly reduced body weight, BMI, body fat percent and waist circumference in overweight or obese Asian populations (-0.37 kg, P = 0.010; -0.27 kg/m2, P = 0.042; -0.36%, P = 0.032; -0.35 cm, P = 0.049) and more significant effects were observed in non-menopausal women reduced body weight (-0.59 kg, P = 0.041), BMI (-0.59, P = 0.041) and waist circumference (-0.59 cm, P = 0.041) in overweight or obese populations. CONCLUSION This meta-analysis showed that soy products have weight loss effects, mainly due to soy protein, isoflavone and soy fiber.
Methodological quality
Jadad score
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4
Allocation concealment
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No
