What's a popular fad diet online. What are the main premises with this diet? Are any foods to be eliminated? Does this require any special foods?

What's a popular fad diet online. What are the main premises with this diet? Are any foods to be eliminated? Does this require any special foods? What are the potential advantages? What are the possible disadvantages? Does this seem safe? Can this be followed long term? If someone you knew was interested in following this diet, what would you tell them before they decide to begin? Thank you.