Many different illnesses can cause an increase in metabolic activity as the body combats illness and disease in order to heal itself.
Hypermetabolism is a common symptom of various pathologies. Some of the most prevalent diseases characterized by hypermetabolism are listed below.
* Hyperthyroidism: Manifestation: An overactive thyroid often causes a state of increased metabolic activity.
* Friedreich's ataxia: Manifestation: Local cerebral metabolic activity is increased extensively as the disease progresses. 
* Fatal familial insomnia: Manifestation: Hypermetabolism in the thalamus occurs and disrupts sleep spindle formation that occurs there.
* Graves' disease: Manifestation: Excess hypermetabolically-induced thyroid hormone activates sympathetic pathways, causing the eyelids to retract and remain constantly elevated.
* Anorexia and bulimia: Manifestation: The prolonged stress put on the body as a result of these eating disorders forces the body into starvation mode. Some patients recovering from these disorders experience hypermetabolism until they resume normal diets. 
* Astrocytoma: Manifestation: Causes hypermetabolic lesions in the brain