fasting:
i've watched others around me do this for at least a day with seemingly little difficulty. from those experiences, i think a lot of people's body's seem able to handle it. i also teach biochemistry, and if a person's insulin is working properly, should be able to handle a fast, for days.
however, if a person has diabetes, prediabetes, insulin resistance, hypoglycemia, fasting can be uncomfortable at best, dangerous at worst. that's my comments from being a biochemist, reading about and teaching this in class.
now my personal experience. i've had blood sugar issues my whole life, been prediabetic for awhile now, have been able to prevent the diabetes thus far, through diet, exercise, and weight management, though its also a challenge. when i don't eat for too long, i develop migraines and just feel really out of it. even fasting 12 hours for blood tests (lipid profiles, blood sugar) is really difficult. much easier if i go to bed right away after i stop eating. and get the blood drawn ASAP after waking up. so that night i sleep as long as possible. so even "fasting" 12 hours for medical reasons can be very difficult for some of us.
there is another reason why i feel someone should not fast. i have gastritis. if i don't eat regularly, the gastritis flares and i have a lot of pain. if i eat regularly, whenever i start to get hungry, normally no problem. i needed blood work done yesterday morning, didn't go to bed right away after eating last meal of the evening, so had to take mylanta before bed, and when i got up. and today, my stomach is still a bit messed up. so if someone has gastritis or an ulcer, i think that's another reason why fasting could be dangerous.
doing a liquid diet (broths, juices, jello) to prepare for some procedures is a little easier for me.
