Can't remember the last time I fasted for even 2 days... But with intermittent and 24-hour fasting the only way I managed to do it was using caffeine. Specifically caffeine pills and home iced green tea, less than 200mg/day. They work wonders and shred through fat in combination with low-/med-intensity aerobic exercise and fasting, and keep brain active. Best done a few times a week only...
Without caffeine I can't fast more than about 16 hours. Specifically I seem to require carbs or go braindead, high protein and any kind of fats (including short-chain fats) don't cut it, and I think too much fasting with caffeine worsened my problems in the medium-term, so I stopped intermittent fasting entirely some time ago. Probably worsened adrenals, thyroid, or god knows what now, and definitely impacts sleep. But of course caffeine had a role in that. It trimmed the fat at least.
I have no doubt fasting can help the immune system but as they point out in the perfecthealthdiet carbs also have a role in immune response. So it must depend highly on the person and type of infection, in terms of whether it will help (or do more harm than good).
Without caffeine I can't fast more than about 16 hours. Specifically I seem to require carbs or go braindead, high protein and any kind of fats (including short-chain fats) don't cut it, and I think too much fasting with caffeine worsened my problems in the medium-term, so I stopped intermittent fasting entirely some time ago. Probably worsened adrenals, thyroid, or god knows what now, and definitely impacts sleep. But of course caffeine had a role in that. It trimmed the fat at least.
I have no doubt fasting can help the immune system but as they point out in the perfecthealthdiet carbs also have a role in immune response. So it must depend highly on the person and type of infection, in terms of whether it will help (or do more harm than good).