Maybe my question is not very clear! Unfortunately, English isn't my language, so I have some difficulty in expressing my ideas.
I'll try to better explain what I want to know!
It's now quite clear to me that under-eating is very harmful, because it causes a more or less severe deficiency of micro- and macronutrients, and therefore it causes a malfunction throughout the body, resulting in occurrence of various symptoms and clinical signs.
We can say that fasting represents an extreme under-eating, and therefore it should have serious consequences for the body, especially if it is very long.
In the light of the above, I'd like to know why many people say that they solved health problems, even serious ones, thanks to fasting!?
I repeat that a scientific answer is appreciated.
i've never fasted intentionally, but the logic (for lack of a better word) in your question is why i chose to juice to lose weight. i won't recommend it to anyone, the decision on their diet for weightloss or otherwise is their own decision. there's an ugly side to any method of weight loss, and i'm sure countless people have failed on all methods including that one. i also did it because i felt i needed to at least lose 30 lbs. in order to be able to have the energy to move about.
now i'm interested in fasting, but more interested in being properly fueled. and i'm still watching the weight come off with some decent fruit calories per day, well over 3K now.
Thanks Dutchie, I'll read it!
I thank you for having responded to me, but the problem of body weight has absolutely nothing to do with my question!
Inter alia, l don't want anyone to stray from my question! I know very well the importance of proper nutrition, the importance of getting enough calories, and everything about the lifestyle recommended on this site.
Here, I just want to know why many people speak about the virtues of fasting.
Assumed that under-eating is bad, I don't see what might be the biochemical mechanisms that make fasting useful, rather than harmful.
Moreover I'd like to get scientific answers!
When you don't eat for about 16hrs the body begins the process of ketosis where it takes calories from fat stores. As we rid ourselves of fat we rid ourselves of toxins as well. This is one reason why people see improvement in health from fasting. Another is that when we fast our body uses the energy we would normally use for digestion toward other more pressing needs, such as cleansing and healing. For example when one is sick with the flu they naturally go into a fast from loss of appetite. And this is helpful for the body and promotes faster healing. If we eat during these times we will likely just be sick longer.
I'm no scientist either, so no scientific response, but think about two things that happen when people fast:
- They can't eat bad foods, so they stop putting toxins in their body
- The body doesn't have to digest food, so it has lots of energy to clean itself
You can get both benefits by eating HCRV too, since you eat good food (little toxins) and it digests easily (more energy). On top of that, you get all the nutrients your body needs.
Perry Fullerton wrote: "...when we fast our body uses the energy we would normally use for digestion toward other more pressing needs, such as cleansing and healing..."
Jules Connelly wrote: "...it spends it's energy healing itself..."
Marco wrote: "...The body doesn't have to digest food, so it has lots of energy to clean itself..."
You all say that, during fasting, the body uses all the energy to repair itself, but according to the theory of the harmfulness of under-eating, cells should go into a state of suffering, during fasting, because of a lack of macro- and micronutrients. So how does the body make the repair process during a fast? The body condition should get worse, not better!
So, are they saying crap, those who support the usefulness of fasting? Or are they right?
When we undereat, we break down a lot of muscle tissue, not just fat. Infact, unless we are eating a high protein diet, we can lose way too much muscle mass when we undereat.
Fasting is a process which evolved not for healing, but for survival. And as such, it is a defensive response to the fact that we waste too much muscle tissue when we undereat. If we have no food (in a famine situation) then we can't go wasting muscle tissue as rapidly as we do when we undereat, because we would become too weak and would quickly begin digesting organs. Evolution is all about improving your chances of survival by finding more flexible ways to meet your needs. So after 3 days (on average) without any food at all, we stop using sugar as the main source of fuel (we break down muscle tissue when starving mostly in order to convert protein into sugar) so that we can conserve protein. Instead, we then begin using more body fat as a source of fuel, allowing the brain to run on ketones instead of sugar. This spares the muscle protein for longer, slowing down the loss of muscle tissue and preserving the organs for a longer period of time, in the hope that we can outlive the famine. We still waste a little protein during a fast, but it is much less. We don't begin using large amounts of muscle tissue for fuel again until all of our fat reserves have been used for energy. This is the true starvation period.
The other reason is that as physiological changes occur in fasting, the body attempts to work much harder to achieve homeostasis (balance) of its organs and functioning systems in order to adapt efficiently to the fasting process. And due to the accelerated breakdown of fat tissue during fasting, there is a greater need to improve the efficiency of the liver detoxification, in order to ensure that toxins released from the fat stores can be managed safely, avoiding damage or death.This triggers all other eliminatory systems, such as lungs, skin, bladder/kidneys etc to improve their efficiency too. It isn't because the body wants to fast in order to heal just for the sake of fasting. It is because it needs to be functioning well in order to survive in such challenging and stressful circumstances (physiologically speaking).
In terms of short-term fasting, when people are eating higher protein diets, often intermittent fasting (eg. one day per week, or 3 days per month, or undereating during every day) is considered to increase longevity purely because it reduces stress on the body from those foods and gives the system a break. But this doesn't really work well on a low protein diet, because muscle protein loss will be accelerated and replacement will be much slower. This creates more chance of problems developing faster.
Thank you so much Adam!
Adam may I ask how little calories does a young female have to eat in order to be categorized "starving" or "losing muscle tissue"? I feel weak when I run up stairs and stuff so I'm worried.
Calories are an estimate of energy requirements. How many someone needs depends on a whole host of things - genetics, metabolism, digestion/absorption, micronutrient intakes, protein intakes, activity levels, sleep, stress. I really can't give a general answer to your question as I don't know the answer. In order to be truly objective, one would have to be keeping track of both food intake by weighing food, as well as body compisition by something reliable like DEXA in order to be sure of that. But if it looks like you are losing muscle mass, then you probably are.If your muscles are getting progressively weaker, then you probably are.
But it is important to realise that insufficient calories are not the only thing that might lead to loss of muscle. Insufficient amino acids will do that too.