Day 3 of the fast . . . so what happens in my body right now?

So, I've never done this before . . . fasted and only drunk water and some skim milk. Surprisingly enough, I don't feel tired or terribly hungry. And it hasn't slowed down my running in the morning.

Makes me wonder a bit, perhaps we evolved to cope with fasting pretty well? I mean, those hunters and gatherers, may not have had food all the time. And they had to run around a lot to find it. So all this eating three or four or five times a day may be just a bad habit?

Then again, it is a lot of fun to eat . . . not having lunch to look forward to is NOT fun.

So I started to wonder what happens in my body when I fast.

There are quite a few studies out there on fasting. Many of them have been done on Muslims, not surprisingly, considering their religious reasons for fasting.

Here is what appears to happen in the body, according to the scientific data:

•Liver glycogen levels are depleted within 8-10 hours. Muscle glycogen falls by 50% over 24-hours, even without exercise.
•After depleting glycogen, amino acids are recycled to be broken down for glycogen through gluconeogenesis.
•We see increases in three of the four hormones driving lipolysis, indicating a propensity towards fat burning. Somewhere around 12-18 hours, lipolysis becomes a major energy pathway, producing energy from body fat.
•T3 levels fall slightly, indicating a slightly lower metabolic rate. Urinary nitrogen excretion falls, indicating less catabolism of muscle proteins.
•Beta-hydroxy butyrate, hGH, and IGF all increase. Proteins that protect cells from stress also increase.
•Inflammatory markers decrease. Insulin sensitivity improves. AGEs likely decrease.
•Cancer protection increases, healthy cells are better protected from chemotherapy, and markers of heart disease decrease. General immunity seems to improve.
•Brain neurons are protected from stressors, BDNF increases (helps grow brain neurons), and the brain is better protected from Alzheimer’s and Parkinson’s Diseases. Fasting after a brain injury lessens the damage of the injury.
•Exercise during a fast shows a higher rate of fat burning for fuel.
•Learning is enhanced and jet lag may be reduced.