The body does a very good job of controlling complicated pathways using many forms of feedback control. Some of the pathways are well understood, others may be unknown.
Despite popular understanding, it would be very difficult for you, now, to intentionally put on one hundred pounds over the next two months or even a much longer time. You would not want to eat that much, and would stop. If forced, when you did the weight actually gained would be far less than predicted. This is because the body, naturally, does stop putting on weight. It does not much like the setpoint being decreased. But it does not care for increases either. Far less than you would think.