Homeostatic theory of obesity

Abstract

Health is regulated by homeostasis, a property of all living things. Homeostasis maintains equilibrium at set-points using feedback loops for optimum functioning of the organism. Imbalances in homeostasis causing overweight and obesity are evident in more than 1 billion people. In a new theory, homeostatic obesity imbalance is attributed to a hypothesized 'Circle of Discontent', a system of feedback loops linking weight gain, body dissatisfaction, negative affect and over-consumption. The Circle of Discontent theory is consistent with an extensive evidence base. A four-armed strategy to halt the obesity epidemic consists of (1) putting a stop to victim-blaming, stigma and discrimination; (2) devalorizing the thin-ideal; (3) reducing consumption of energy-dense, low-nutrient foods and drinks; and (4) improving access to plant-based diets. If fully implemented, interventions designed to restore homeostasis have the potential to halt the obesity epidemic.

Keywords: body mass index; diet; food; obesity; theory.

Figure 1.

Prevalence of obesity in adults (aged 16 years and over) by household income quintile, Health Survey for England, 2008–2012.

Figure 2.

Physiological homeostasis. A: Equilibrium: The person feels neither hot nor cold, the skin receptors detect temperature in the normal range, there is no need to generate a response and so the effectors do not generate sweat. B: Loss of equilibrium: The temperature is high (disequilibrium), the skin receptors detect that the temperature is too high, the control centre sends signal along an efferent pathway to cool the skin down, the effectors generate sweat, the skin returns to equilibrium.

Figure 3.

Psychological homeostasis. A: Equilibrium: The person feels physically healthy, feels no necessity to regulate consumption and eats and drinks freely without restriction or restraint. B: Loss of equilibrium: The person feels physically unwell, ‘out of sorts’, sad, stressed or worried and decides to eat and drink carefully to restore normal physical health, leading to a return to equilibrium.

Figure 4.

The Homeostatic Theory of Health. Feedback loops in a variety of systems provide functional equilibrium with set-points for physical health, subjective well-being, affect, consumption and other processes. In many instances, feedback loops operate reciprocally; in other instances, feedback operates in one direction only, for example, from attachment to subjective well-being, physical health and affect.

Figure 5.

The Homeostatic Theory of Obesity. In overweight and obesity, feedback loops in different homeostatic systems that operate to maintain equilibrium become imbalanced. In one of these systems, the levels of body dissatisfaction, negative affect and high-energy, low-nutrient consumption run out of control.

Figure 6.

The Circle of Discontent. A system of feedback loops causes a state of disequilibrium that is difficult to control. Pathway 6 is shown with dotted lines because evidence is inconsistent.

Figure 7.

Treatment and prevention of obesity as a restoration of homeostasis.