Abstract
Obesity is one of the major health-threatening conditions nowadays. Nigella sativa (NS) is a medicinal plant that demonstrates multiple therapeutic effects. In the current review, we aim to evaluate the weight lowering effect of NS in both clinical trials and experimental studies and to explore the possible reported mechanisms of this effect. We searched PubMed and Web of science and retrieved 14 clinical trials and 5 experimental studies that justify our inclusion criteria. After the analysis of these articles, we can conclude that long-term administration of NS for 6-12 weeks can significantly lower bodyweight and other anthropometric indices. NS-oil is more potent than NS-powder in lowering bodyweight probably due to the higher concentration of fatty acids and thymoquinone. The weight lowering effect of NS is not a toxic effect, it conversely and preferably lowers the elevated liver enzymes in condition of fatty liver. It is also frequently accompanied by positive metabolic modifications, such as enhancement of lipid profile, lowering blood glucose and improving insulin resistance. Possible mechanisms for NS-bodyweight lowering effect might include an appetite-suppression effect, lowering caloric-intake and inhibition of intestinal glucose absorption. However, further experimental evidence is required to support these mechanisms or unveil new ones.