This article from the New York Times of 30/12/19 is a very good summary of what it's all about. And it includes a "7 Day Challenge" for newbies &/or backsliders :-)

https://www.nytimes.com/2019/12/30/well/eat/sugar-diet-healthy.html 

In case you have trouble accessing the article i attach a saved/edited version. Sorry the system says my upload limit has been exceeded which can't be  true as the file is only 45kB :-(