I have taken an interest in diabetes recently, and done some reading.
Fasting has a regulatory factor, improving patient outcomes. Here are some statistics.
I believe that humans are evolved to experience periods of fasting followed by periods of overindulgence, in response to hunting and harvests, and that such patterns are required for conditioning of the feedback loops in the body. Continuous steady overconsumption of food leads to overstimulation of certain feedback loops, and under-stimulation of others, resulting in the body’s loss of ability to regulate itself.
And I think to myself, it’s been quite awhile since I’ve been really hungry.
The feeling of exercising while hungry must have been familiar to our ancestors on the savannah. Surely they did not have a little something to eat before going out on a hunt, but rather must have gone hunting because they were hungry. My own experience and that reported by my friends who also train martial arts is that exercise suppresses appetite.
Doing some research on PubMed, I find that exercise actually _increases_ blood glucose. https://www.ncbi.nlm.nih.gov/pubmed/23835594
This was counterintuitive to me because glycolysis would have suggested to me a reduction in blood sugar. But, the body actually responds to the increased energy requirement by making more available. (The body is responding to a perceived energy deficit by increasing available glucose. Also a symptom of T2D.) The particular study involved a “format of exercise was found to be well tolerated in an overweight population,” but was nevertheless intense, involving intervals above anaerobic threshold (VO2 Max). Most people I know hate to even break a sweat.
Advice from personal trainers is that one must exercise longer than 30 minutes to start to lose weight (read: burn fat, or ketosis). I wonder if glycolysis actually promotes ketosis, and ketosis inhibits glycolysis. There must be some complex molecular signaling involved. Type 2 Diabetics are stuck in a runaway ketosis. Their bodies are stuck in starvation mode – blood sugar is elevated because their cells are not getting enough energy, or unable to metabolize the glucose that is there, and they must get their energy from burning fat, resulting in weight loss even with increased food intake.
So I have been experimenting on myself. What happens when I eat foods with high glycemic index, like potato chips or bread? I feel hungrier. I suppose the mechanism is: blood sugar goes up, insulin production increases. blood sugar drops. I feel hungry.
What happens when I exercise? blood sugar goes up in anticipation of increased energy requirements. I feel less hungry.
I usually eat following exercise. Exercise without eating would also have been a familiar feeling to our ancestors on the savannah – suppose they went on a chase, but did not catch the game they were chasing. What happens when I do this? I seem to sleep well, but wake up very early. I don’t experience diminished energy. (I’m used to training Aikido and average three times a week, so I’m already exercising more than most people I know – your mileage may vary.)
Yesterday after training I just had a banana. Think: potassium.
Today after training I had 50g of peanuts: High-fat.
I actually don’t feel hungry right now, although I did before training. I’d had cake and cookies at 4:30pm, and training started at 7pm.
Why am I doing this? I’m trying to learn more about my body. If eating high-glycemic index foods makes me hungry, maybe I shouldn’t eat such foods. Also, I’m experiencing the feeling of hunger, and finding that I can tolerate and adapt to it. (Much like cold showers in the winter.)
I am also interested in what effect it will have on my body fat and muscle. Will I store more fat as my body responds to a nightly calorie deprivation? or will my body become more efficient at storing and burning both glycogen and fat, resulting in a better ability to build muscle (as muscle requires a lot of energy).