• Human growth hormone increases during fasting.
  • Resting energy metabolism increases during fasting, unintuitively.
  • You should enter ketosis within a few days of fasting.

Observations on hunger:

  • You’ll tend to be very hungry throughout the first day, but this will subside in subsequent days.
  • You do not get hungrier as time goes on. Paradoxically, it tends to decrease further in the future for short-term fasts.
  • Ghrelin spikes at expected eating times, but subsides over a few hours after.