MAPK8 and obesity due to melanocortin 4 receptor deficiency: However, the meta-analysis by Jafarirad et al., including 8 trials with 449 participants, did not show any significant effect of curcumin on weight, BMI, and waist circumference [48].It has been revealed that the Janus Kinase (JNK) enzyme is regulated by curcumin, which plays an essential role in obesity pathogenesis.