People with Parkinson’s disease tend to have increased metabolic rates: That is, the body burns more energy at rest than the normal body does. In many people with Parkinson’s, tremor or medication induced dyskinesias are readily identifiable causes, but for many others the reasons for this phenomenon are unclear. Many scientists believe it is primarily a manifestation of mitochondrial dysfunction. Mitochondria, small structures within cells, produce the energy sources that cells need to function. The main source is a chemical called adenosine triphosphate (ATP). Researchers suspect that disruptions in the MITOCHONDRIAL electron transport chain known to occur in Parkinson’s disease affect many aspects of metabolism.
Metabolic needs increase under numerous circumstances in health, such as during pregnancy and as a result of moderate to strenuous physical activity. The normal mechanism for responding is an increase in appetite, which causes the person to eat more and supply additional calories to the body. The person with Parkinson’s has various impediments to this mechanism, including changes in taste that affect preferences and the desire to eat, difficulty with the mechanics of eating including chewing and swallowing (foods that are nutrient-dense also are more difficult to eat), and slowed gastrointestinal function (as a result of the neuro-muscular effects of the Parkinson’s and associated degeneration of the autonomic nervous system). Many people acquire a craving for sweets in the later stages of Parkinson’s, which some scientists believe is the body’s attempt to increase caloric intake to accommodate increased metabolic needs. However, the result is further disruption of metabolic processes because carbohydrates alone cannot supply the body’s nutritional needs.