Stay Up to Date! Like us on Facebook  and Twitter  for the latest news and announcements    

Fasting Tolerance

When calorie intake drops, as during infections or with prolonged fasting, glycogen is first mobilized to provide glucose as a source of energy.  When glycogen stores are used up, gluconeogenesis and fatty acid ß-oxidation are initiated.  A proportion of patients with primary mitochondrial disease show secondary fatty acid ß oxidation dysfunction (Bennett, 1993; Hagenfeldt, 1998; Enns, 2000).  This may present as fatigue or lethargy or vomiting with prolonged fasting or long periods with inadequate calorie intake.  When an affected patient becomes ill, energy requirements rise and calorie intake usually falls, and patients can become symptomatic. 

If a patient wakes up tired in the morning after a full night's sleep, the possibility of a sleep disorder should be considered since obstructive sleep apnea is not unusual in patients with energy problems.  Another possibility is fasting intolerance (so that the early morning fatigue is related to having fasted overnight), perhaps due to the suboptimal availability of fat as an energy source (due to fatty acid oxidation dysfunction).

When fasting intolerance is a consideration, a trial of complex carbohydrates at bed-time may be provided with the objective of improving morning lethargy.  Uncooked corn starch is such a slowly-absorbed complex carbohydrate which delays the onset of fasting, shortening the duration of the overnight fast, and reducing the demand for fat as an energy source.

Page Security: