Seven and a Half

Human It is now 7:30 pm on the 17th. I decided to play a game with you, Very simple, At 7:30 pm on the 18th, The half of the world's people with higher fat mass, will die. " ------------- Seven days, seven and a half, "what" is using cold hard indicators to determine the fate of all living beings? How will Lin Wei, who goes to the island to attend a class reunion, become the 50 million survivor among 7 billion people? Or maybe he has other choices...