What is the Set point theory in the management of weight?

What is the set point theory in the management of waste? So for me, the easiest way to explain this is to use an analogy and the one that I think works best is, for example, every one of us has a thermostat in our house, in our home which controls the ambient temperature. Any good thermostat, as the temperature goes up, it switches the heating off, and as the temperature goes down, it switches the heating on. Similarly, imagine that your body has a set control for weight, and let's just call it a weight attack, to help our understanding. This controls your weight at a set point. Every time you do a diet, yes, you may lose a little bit of weight, but your body will fight that and resist that and it will do things for you to stop losing that weight and gain the weight back to its set point. So, for example, that could be increasing your hunger levels or reducing the rate at which you burn calories. All these physiological changes will take place that will resist the weight that you're losing from the diet and tend to push your weight back up to a success point and unfortunately this happens and this is why people who diet are always struggling to maintain their weight loss.