From an article on medical issues for Ramadan fast. But may apply here.
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Total fasting reduces or eliminates hunger and causes rapid weight loss. In 1975, Allan Cott in his
"Fasting as a Way of life" noted that "fasting brings a wholesome physiological rest for the digestive tract and
central nervous system and normalizes metabolism."
It must be pointed out, however, that there are also many adverse effects of total fasting. That includes hypokalemia (potassium deficit) and cardiac arrhythmia associated with low calorie starvation diets used in unsupervised manner.
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Those with severe hypertension or heart diseases should not fast at all.
Those with Migraine Headache: Even in tension headache, dehydration, or low blood sugar will
aggravate the symptoms, but in migraine during fasting, there is an increase in blood free fatty acids,
which will directly affect the severity or precipitation of migraine through release of Catecholamines.
Patients with migraines are advised not to fast.
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