In November of 2007 a study was published in the journal Cell in which it was revealed that resveratrol administered orally to mice significantly increased the number of mitochondria in the mice's cells (Mitochondria are the organelles within the body’s cells that generate energy).

Not only did this increase in mitochondria double the mice's endurance, but it also increased the mice's metabolism; In essence, with increased mitochondria levels, the mice were able to burn more calories, and thus avoid weight gain.  
 

A lead researcher of the study, Johan Auwerx, said a study of men and women from Finland revealed that resveratrol will likely produce similar results in humans.