Should obesity be treated as a disease?

Obesity can be caused by injury or medicine

Question: Should obesity be treated as a disease?
Position‹2 of 3›: Obesity is not a disease
Argument‹2 of 3›: Obesity can be caused by injury or medicine

A disease is not something that can be caused by external factors.

The argument

A disease is something like cancer, heart disease, or dementia. There are medical long-term illnesses caused by pathogens or genetic disorders. Obesity is most often caused by a lack of motivation and unhealthy food. Something caused by factors like that cannot be a disease. What if someone is obese because they are paralyzed and cannot exercise? Or if someone is taking medicine that causes weight gain? These are not things that are considered the beginning of a disease.

Premises

[P1]Diseases like cancer, heart disease, and dementia are long-term illnesses caused by pathogens or genetic disorders. [P2] Obesity is most often caused instead by a lack of motivation and unhealthy eating, which cannot make it a disease. [P3] Even when obesity follows from an injury that prevents exercise or a medicine that causes weight gain, those causes are not the onset of a disease. [C] Therefore, because obesity can be caused by injury, medicine, or lifestyle rather than pathology, obesity is not a disease.

Counter-arguments

Diseases like cancer can be caused by outside elements (e.g. carcinogens). Just because obesity is caused by things like diet and exercise doesn't mean it cannot be classified as a disease.

Rejecting the premises

[Rejecting P1] If cancer can be caused by outside forces such as carcinogens, then obesity can be classified as a disease.