When your cell’s are in stress metabolism mode, there will be different pathways activated when compared to the slightly different fasting metabolism mode.
If there is an infection of say, pneumonia present in the organism an immune response will take place. Macrofages will multiply in numbers activating cytokines, a form of message molecule requesting a certein response in certain cells. Tumor necrosis factor alfa (TNF-ALPHA) and Interleukin 1 and 6 (IL-1, IL-6). These cytokines will set of an effect, putting the organism into a state of stress metabolism.
Metabolic stress is not confined to infections, it can also come from surgical stress, burns, traumas, or from necrotic tissue from any cause.
We’ll see a highly increased secretion og Cortisol, Glucagon and Adrenalin. Ketone bodies will stay unchanged or only slightly increased. Insulin will increase, and insulin sensitivity will dramatically decrease, meaning blood glucose will go up.
Hunger will be felt less, and muscle mass will get broken down quickly.
The muscle mass breakdown is a result of a strong increease in gluconeogenesis – the production of glucose in the liver, using protein as buffer. If dietary protein is not sufficiently present, breakdown of muscle will take place. So an increase in the production of glucose and a decrease in insulin sensitivity means that less glukose will actually be available to the cell, and more glucose will be present in the blood stream. If a pathogenic bacteria is present somewhere, it will have good ressources of free glukose in the blood stream.
Lypolysis is sligthly increased during stress metabolism, just as it is during fasting metabolism. Lipolysis is the breakdown of triglycerides, but that form of energy production can not take place in the brain cells. They’ll have to be broken down further to ketones in order to be usefull to neurons.
But unfortunately, during stress metabolism, ketogenesis is only slightly increased.
My bet is that glukose is still the main energy source during stress.
But, as insulin sensitivity is already down a notch, and gluconeogenesis is upregulated, dietary glucose is hardly nessesary. If not directly damaging.
Now I am a nurse student, and I have been out in the field 4 months in all in a trauma and ampution ward. I have seen metabolic stress. High pulse, high breathing frequency, decreased hunger. Muscle wasting. I see a huge problem, and let me get to the point by making a fictional patient.
John is 70 years old, insulin dependent type 2 diabetic, overweight. He is aware that he should be drinking sugar free beverages. The doctors are strongly considering amputating his right leg below the knee. Of course he is sad by the probable loss of a leg, but there is a really bad blood flow, and it is almost numb to sensations. Either way, if not amputated, necrosis will probably spread in his leg.
He has been lying in bed for a week now, not moving around a lot, and not a lot of hunger. He is also in risk of pneumonia, which for an immuno surpressed individial can be lethal. Lying down a lot will close of respiratory flow in some parts of the lungs, giving favorable growth condotions for a pneumonia. Further, he has been a smoker until the hospitalization, meaning the cilia function in the lungs are not able to sufficiently transport pathogens up and away.
Every morning the nurse will ask him if he wants toast, oatmeal and youghurt. Toast, full of simple carbohydrates which will instantly be broken down to glucose molecules. Youghurt, full of sugar in the form of lactose. Oatmeal, a high carbohydrate meal which will give him all the glucose he is already producing. Bread, rice, potatoes, pasta the rest of the day, and maybe a protein shake if the nurse insists.
Do you see the paradox? Pathogens are glucose dependent, and he is not very good at getting glucose into his cells. Yet he eats glucose all day, all the while his body needs protein for gluconeogeneses and for the growth of immunecells and red blood cells and so on. The free glucose in the blood is a free meal for the bacteria and fungi, cancer cells and what not.
Unfortunately, he is not informed very well. Muscle wastes away and he doesn’t have the muscle power needed to get moving, making his bed a jail for him.
At this moment in time I’m fasting 16 hours a day, maybe 5 days of the week.
Fasting is not as catastrophic a response, rather, it has huge benefits such as autophagy. A proces where autophagosomes, organelles in the cell which eats away the least usable cell components in the best darwinian selektion fashion. The Proteins which are improperly folded will we eaten away, making the whole cell unit stronger in the best natural selection manner. More on fasting benefits another day. Today I’m going to talk about the metabolic pathways of fasting.
During a fast, this means not eating calories for 12-14 hours we will see a strong increase in ketogenesis, meanning the brain will have plenty of fuel. Ketone bodies easily travels through the blood brain barrier and is the only thing next to glucose that the brain cell can utilize for energy.
During a fast, we won’t see the increase in pro inflammatory cytokine TNF-ALPHA, IL-1 and IL-6. Insulin production will go down, no need for insulin to mobilise glucose into the cells when glucose is not available in great quantities. Besides, the glucose utilized in most neurons is not facilitated by insulin, but by other means through GLUT-1 and GLUT-3, glucose transport molecules. So the glucose available will easily be consumed by the brain, but gluconeogenesis is only slightly increased during a fast. That means, not too much muscle waste, in fact, there might even be muscle protective fuctions of fasting, an example being the increased production of Human Growth Hormone. I think this depends on whether the muscles are stimulated during a fast – if stimulated suffiecently, I hypothesize that it might be a signal to the body to not eat away muscles. This is from my own experience with intermittent fasting experimentation for more than a year.
Lipolysis, is increased just as it is in stress metabolism, so lipids are of course burned more when glucose is unavailable.
The katabolic hormones, Cortisol, Adrenalin, Glucagon, are slightly increased, but not as much compared to stress metabolism. The body might get a little colder during a fast, as we will se a decrease in the metabolic rate, compared to an high increase during stress metabolism.
So all in all, fasting is much easier on the body, not so much nitrogen/protein loss, no systemic inflammation. No excess glucose in the blood, not a very good growth environment for pathogens.
The thing about fasting is, it is very hard on you if you’ve never gone without glucose for more than 16 hours. If the body has not adapted to fat burning, it will take a while to upregulate the lipolytic enzymes. Most people are totally carbohydrate dependent, but the but will adapt to fasting and in fact, now that I do not eat for 16-18 hours everyday, it is in fact pretty easy, if not enjoyable to not cook all the time.
I can say that to me, excess appetite is mostly psychological – I’ve basically been cultured to eat all the time.
So to sum up my main arguments. When sick, or after a surgery or physical trauma, get some protein. The body will consume protein, and if it is not available from the diet, it will eat away muscle.
Starve yourself when you’re healthy and your protein needs are met in the feeding phase of the day. If the protein needs are not met when sick or damaged, that might be catastrophic to your health. But – Eating all the time when healthy will also be catastrophic, but I’ll get into the benefits of fasting later on.
– A. Seabridge