It's time to pull together all the seemingly disjoint threads in the previous chapters into a unified whole. We already know what we need: a proportional control negative feedback system that tells how much to eat. All the pieces of that system are now in hand. We need only hook them up into this; the solution to the problem of weight control.
As you'd expect, the system forms a closed loop. Many of the words are familiar. Let's take a detailed look at how it fits together.