A very useful concept to understand the mechanisms that control body weight changes is the Setpoint.
The Setpoint is a kind of body weight thermostat that is
set genetically and regulates weight near a fixed point by a complex feed-back mechanism.
The relatively steady Setpoint operates in spite of possible
attempts people can make to try to modify their weight deliberately.
Internal metabolic weight control works therefore by regulatory mechanisms that are very similar to the ones used by other control systems in our bodies that are used to guarantee a constancy of internal environment despite strong external environment changes.
Various kinds of mechanism are, for example, the thermic adjustment system or the sugar adjustment of the blood systems, and the circulation of the blood control systems.
This means that each time we try to modify our weight we actually fight against the powerful control mechanism.
Since it does not seem possible to reset the Setpoint, the result will be that when we end our efforts to maintain our weight at an altered level, the Setpoint will tend to take the weight back to the original values.
Briefly, a lot of effort without permanent results.
The Setpoint concept helps us therefore to understand that it is important for the genetic component to be in play in the development of obesity.
It has been suggested that, since obesity predisposition seems linked to genetic factors shown by studies on twins, the
involved factors could be a congenital alteration of the Setpoint that in obese people may be pathologically regulated too high.