Which of the following best expresses the essential information in the highlighted sentence in the passage?

A Ketosis causes weight loss at first, leading people to wrongly believe that they are losing fat.

B Ketosis causes the rapid loss of fat at first, which leads to a false belief that the loss will be permanent.

C The process of ketosis quickly misleads people into thinking that they are losing weight.

D Ketosis causes rapid weight loss, but only in the early days of the diet.