“…'Principle I (Agency)' states: 'The voluntary behaviour of conscious organisms is guided by a universal striving for equilibrium, a striving with purpose, desire and intentionality' (Marks, 2018: 11). 'Psychological homeostasis' is specified as the equivalent of physiological homeostasis described by Bernard and Cannon. As already mentioned, the theory was first proposed as a theory of obesity (Annunziato and Grossman, 2016;DiClemente and Delahanty, 2016;Marks, 2015). Several empirical studies and reviews have supported the obesity theory, for example, Jumbe et al ( 2017 The inverted-U shaped curve is of particular relevance to this theory of well-being because a Gaussian, inverted U-shaped curve can be guaranteed to be the product of any homeostatic system (Chrousos, 2009), which I discuss next.…”