Mental illness can cause obesity

The argument

The claim is not that everyone who is obese has a mental illness, but that a recognisable route into obesity runs through psychological causes, and that when it does, the resulting condition satisfies the criteria used to identify mental illness. Start with the causal pathway. Individuals who eat poorly in response to depression do not necessarily stop once they are treated: many continue to overeat once they are on medication, because an increase in appetite is itself among the effects of the treatment. The eating that began as a response to the illness is then sustained by the response to the illness. A comparable pattern appears where poverty is the driver — easy accessibility to unhealthy food combines with the stress of living in poverty, and the two together produce prolonged overeating rather than an occasional episode. The second step applies the diagnostic criteria. Mental illness usually has a reason or a trigger, and to be diagnosed with one, symptoms must have lasted several months. Both conditions are met here. The trigger is identifiable — depression, or the stress of poverty — and the duration is not in doubt, since obesity is certainly not something that can come and go in less than a month. Whatever else is true of it, it is not a transient state, which is precisely what the duration criterion exists to exclude. Put the two together and the classification follows. Mental illness can be a reaction to a stressor or trauma. If the stressor is poverty and the reaction is overeating, then the behaviour and its consequence have exactly the structure the diagnostic framework describes: an identifiable trigger, a maladaptive response to it, and persistence over time. On that reasoning obesity arising this way can be defined as a mental illness, rather than treated as a simple failure of willpower or as a purely physical disease.

Context

Poor mental health causes many problems with weight. Depression causes a lack of motivation to eat healthily or exercise in many cases. In addition, many antidepressants, antipsychotics, and mood stabilizers cause weight gain and hunger.

Premises

Counter-arguments

Obesity is a result of mental illness, not the source. Depression causes weight gain as do many antidepressants. School is a source of anxiety, and anxiety is a mental illness. But school isn't a mental illness and neither is obesity.

Rejecting the premises

[Rejecting P1] Obesity is the result of mental illness, not the source.