https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.70074
ABSTRACT
Some evidence suggests that resveratrol may have anti-obesity effects on diabetic patients; while other studies have not confirmed this claim. This study aimed to systematically review the literature and evaluate the impact of resveratrol supplementation on body weight, body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and hip circumference (HC) in individuals with type 2 diabetes (T2D). We conducted comprehensive searches in electronic databases such as Web of Science, PubMed, Scopus, and the Cochrane Library up to February 2023. We included randomized controlled trials (RCTs) including adult T2D patients who received resveratrol supplementation and reported at least one anthropometric measure. Two independent researchers performed data extraction and quality assessment. We determined overall effect sizes using a random-effects model and assessed heterogeneity using the I 2 statistic and Cochrane’s Q test. A total of 11 trials with 614 participants were included. The pooled effect size showed that taking resveratrol supplements significantly decreased body weight (WMD: −0.44 kg, 95% CI: −0.88 to −0.00, p = 0.048), BMI (WMD: −0.19 kg/m2, 95% CI: −0.37 to −0.01, p = 0.03), and WC (WMD: −0.80 cm, 95% CI: −1.35 to −0.24, p = 0.005). However, we did not find any significant effects on HC or WHR. This meta-analysis revealed significant reductions in body weight, BMI, and WC among T2D patients who consumed resveratrol. However, there was no significant effect on HC and WHR. Further high-quality, long-term studies are necessary to confirm these findings.
So it statistically significantly reduced weight and BMI, by what I would see as an insignificant amount.
440grams is really not something I would consider a significant weight loss even if it is statistically significant.
I bought a special weighing machine to weigh myself as normal domestic machines have an error of perhaps 300g in any event. This is the sort of machine that is used for martial arts contests and is accurate to 50g, but importantly it will come out with the same value when you do sequential weights.
If you have a weighing machine which when you stand on it and move around slightly (only slightly) and it does not change then it is lying to you.
(same principles apply to BMI)