A Substitute For Fasting - For Weight Loss

http://www.washingtonpost.com/news/to-your-health/wp/2015/06/22/heres-how-a-five-day-diet-that-mimics-fasting-may-reboot-the-body-and-reduce-cancer-risk/: 

Is this what is the basis for the various ways (South not north) Indians fast? I refer to the term called upwas / vrat.