Here's a generic Hypothalamus-Pituitary-X Axis loop, where X may be thyroid, adrenal, gonadal etc.
Negative feedback control systems can overshoot, especially if there's a delay in the feedback path that's longer than the rise time of the input step.
An example of this is the first-phase insulin response. Loss of the first-phase insulin response occurs in over-fat people who are hyperinsulinaemic. Without the first-phase insulin response, there's a delay between an increase in blood glucose and an increase in insulin secretion. A rapid upwards step in blood glucose (say, from eating a high-GL meal) causes a massive overshoot in insulin secretion, resulting in postprandial sleepiness, also down-regulation of insulin receptor activity in the appetite centres of the brain, causing ravenous hunger when the insulin level falls to normal.
See also Blood Glucose, Insulin & Diabetes.
People shouldn't be too quick to write-off the knowledge of an Electronic Engineer who's delving into the mysteries of the human body.