Part 1: What Happens To Your Body When You Fast? – Energy Production
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Today, we Skribit. The question of the day, with 184 votes, is a very interesting one. It is:
Physiological processes during fasting
As you know, I’m a big fan of intermittent fasting, but this is an area of it that I’ve never really looked at. I’m going to break this into several posts because there’s a lot going on here and I don’t want to burden everyone with a novella. Today, we’ll look at how the body handles energy production during the fasting period, a good starting point given that, when you get down to it, an energy source and water are the only two requirements for the body to operate.
First things first, let’s define fasting. A simple timeline showing the various states of the body will be useful here (baseline is the end of the previous meal):
- Up to about 3 hours: the “fed” state
- From 3 to about 12-18 hours: the “postabsorptive” or “early fasting” state
- Up to about 2 days: the “fasting” state
- Beyond 2 days: “starvation” state or “long-term fasting”
We know what happens in the “fed” state. The body is digesting the food consumed in the previous meal, generating energy from the carbohydrates and fats ingested and depositing excess as stored glycogen and fat. Where our interest today lies is in what happens after those three or so hours of digestion and energy storage.
Energy Production
So let’s turn our attention to what goes on from about 3 hours post-meal onward. At a base level, the body begins digging into stored forms of energy to supply its needs. The three forms of stored energy in the mammalian body are glycogen, amino acids (protein), and adipose tissue (fat).
Glycogen
I’m sure I’m not surprising anyone here by noting that the body stores glycogen. Glycogen is a polysaccharide form of glucose, stored in both the liver and in the muscles. Due to the lack of the glucose-6-phosphatase enzyme, muscle glycogen is only available to the muscle in which it is stored (i.e., the biceps cannot tap into the glycogen stored in the triceps or the calves), but liver glycogen is readily available to any body cells. The brain is a prodigious consumer of glucose, gobbling up nearly 60% of the body’s blood sugar.
After digestion, the liver begins releasing its stored glycogen to the body for use in running the brain and other systems. A study in rats showed a marked decrease in liver glycogen (see Table 3) during a 24-hour fast. In fact, rats on a normal ad libitum feeding schedule showed a more than 100-fold difference in liver glycogen stores (138.4 mg vs 1.3 mg for the fasted rats). Muscle glycogen is also somewhat depleted during a fast as glucose is used to fuel daily activity. Simple 24-hour fasting, without inducement of exercise to deplete muscle glycogen, brought muscle glycogen down by about 50%.
In humans, just the overnight fast of sleeping is enough to nearly deplete liver glycogen. That big brain doesn’t stop working and sucking up glucose just because you’re unconscious.
Amino Acids
When the body runs out of glycogen in the liver to fuel the brain, it turns to amino acids. Through the process of gluconeogenesis, the liver breaks down these proteins to create glucose. Before the bodybuilders in the crowd pass out at the thought of losing a single ounce of their hard-earned muscles, the interesting thing here is that the body isn’t necessarily using muscle proteins at this stage. The liver is able to meet most of its glucose needs by recycling lactate and alanine.
Around the eighteen hour mark, when we move into the “fasting” state, muscle proteins become the chief source of amino acids to fuel gluconeogensis. The breakdown of fat stores through lipolysis (next section) also provides glycerol, which the liver converts into glucose. While I can’t find anything on this, I don’t think a bit of muscle protein breakdown is necessarily a bad thing, so long as your lifestyle is typically anabolic. I’d think that allowing the muscles to consume worn out proteins allows for better rebuilding of new muscle fibers, clearing out cellular junk. I may also be completely out in left field (Anyone have anything on this? Bueller? Bueller?).
To continue this ramble, another interesting thing is that not all amino acids are broken down for glucose. Some are known as ketogenic amino acids. In humans, the two aminos that are always converted to energy through ketogenesis are leucine and lysine. Threonine, isoleucine, phenylalanine, tryptophan, and tyrosine can go either way, being broken down for either ketones or glucose as needed.
I, and many others around the CrossFit and Performance Menu forums, have found an increase in muscle mass and a decrease in fat mass during our experiments with fasting. I have to wonder if a low-carb diet with fasting versus a typical high-carb diet with fasting has any effect. Low-carb diets tend to be protein-sparing. While the body still needs glucose, the increased protein intake on a low-carb diet supplies the necessary amino acids to generate adequate glucose.
Adipose Tissue
Lipolysis is the process of mobilizing fat from the body’s adipose stores for breakdown into usable energy. There are essentially five main hormones controlling this process: epinephrine, norepinephrine, glucagon, and adrenocorticotropic hormone (ACTH), along with insulin. Insulin is the great regulator; as we know from our biochemistry textbook (or from Good Calories, Bad Calories), when insulin is up, fat mobilization is down. The other four hormones are lipolysis inducers.
First, let’s look at the regulator, insulin. During fasting, insulin drops due to the lack of incoming calories from the gut. Along with that, blood glucose levels decrease to baseline. With no influx of glucose and fatty acids coming from the gut, there is no need for the storage hormone.
What about the other four hormones, the ones stimulating lipolysis? We see an increase in ACTH, along with an increase in cortisol, at least in Ramadan-style fasting of eating breakfast before sun-up and dinner after sun-down with nothing in between, a fast of approximately 13-14 hours. We also get an increase in epinephrine, further driving lipolysis. Norepinephrine is much less potent in stimulating lipolysis than is epinephrine and from what I’ve found, levels of norepinephrine don’t appear to change much during fasting.
Throughout the animal kingdom, fasting increases glucagon levels. It happens in humans (Page 242). It happens in rats. The garden warbler, a bird (and therefore, not a mammal), also sees an increase in glucagon during fasting. That means absolutely nothing to two-legged, non-flying mammals like ourselves, but it is interesting that Nature uses similar mechanisms throughout its branches to alleviate the same issues.
Wrapping Up
The really exciting part of this is that we’re seeing these hormonal changes around 12-14 hours of the fasting period. Once the body has digested and stored or burned the previous meal, it begins cranking up other methods of meeting its energy needs. I think this is why so many are seeing positive effects from regular fasts of 15-24 hours. The body uses all of its energy systems, taps into stored fat, and never gets too much time to tear into the muscles. As I understand it though, these short fasts don’t allow the body to get fully into ketosis with a full switch to lipolysis for energy. Again though, I wonder how a low-carb diet affects the rate at which the body turns up the lipolysis.
I’ve tried to simplify this to a level that both you and I can understand. I’m not 100% sure that I digested what I read and spit it back out entirely correctly. If I’m off on something, please correct me. What did I miss? What questions does this generate?
Table of contents for The Physiology of Fasting
- Part 1: What Happens To Your Body When You Fast? – Energy Production
- Part 2: What Happens To Your Body When You Fast? – Playing With Hormones
- Part 3: What Happens To Your Body When You Fast? – Inflammation and Blood
- Part 4: What Happens To Your Body When You Fast? – Healing and Longevity
- Part 5: What Happens To Your Body When You Fast? – Exercising and The Rest
- Part 6: What Happens To Your Body When You Fast? – Q&A
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Scott,
Nice summary. This may be covered in a future part, but I was under the impression that increased cortisol (during fasting, or otherwise) is a bad thing (this is primarily from reading MOD’s blog and posts). Just wondering.
Scott
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Hey Scott,
Love your blog. I read every post.
My latest dietary changes back you up on this somewhat. I started experimenting with IF around 2 months ago with ~18 hr fasts on weight lifting days(3x per week). 5 weeks or so I changed it up to make 2 of those ~23hr fasts by skipping lunch too, also on lifting days. As a result I gained ~3.5 pounds of lean mass while losing a half a pound or so of additional fat. By gaining muscle during this I don’t see how my muscles were consumed by the fasting. There was little else I changed other than adding the IF.
My personal opinion is that we should be doing IF and not eating 3 squares a day all the time. I feel that there are protective routines that are running for me now that never have, but maybe I am imagining things.
Please keep up the excellent posts.
jeff
PS Quick question. Can you comment on the combination of intense exercise on fasting days? My sense is that I am using up my stores faster and thus force the ketosis sooner, but I am not sure if that makes sense.
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Scott,
Great post, as usual.
As far as the age-old body building fear of “losing muscle” due to lack of protein ingestion, I can say through personal experience that these fears are largely unfounded. I experimented with intermittent fasting (24 hour fasts, twice per week) for much of last year, and I can honestly say I actually made gains in muscle mass, rather than lose any significant amount.
Again, I can’t say I’m 100% sure of the science, but I think a lot of it was primarily due to how anabolic the body becomes when it is in a fasted state. When a person incorporates weight training into their weekly regimen, it’s almost like the body becomes a ’super sponge’ of amino acid absorption.
Lastly, we should note that the body is constantly breaking down muscle and re-building it. As I type this post, I’m no doubt ‘losing muscle mass’. The important thing to remember though, is that as long as one resistance trains regularly, and also ensures that high quality protein is eaten at every meal (regardless of when these meals are eaten), permanent muscle loss is highly unlikely.
We just need to distinguish between a ‘fast’, and extended periods of starvation.
-Steve
http://www.becomingAdonis.blogspot.com
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I’m really curious about the brain and it’s use of glucose. Children with epilepsy are sometimes put on ketogenic diets, and there have been studies on Parkinson’s patients on ketogenic diets, the theory being, I believe, that the brain using ketones instead of glucose helps with the systems of both diseases. In those cases, is the body still converting protein to glucose and the brain is using that? And if the brain is actually using ketones instead of glucose, at which point duing a low-carb diet/fasting does that start happening?
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Hey Scott,
Don’t forget the main source of ketones during fasting: the breakdown of fatty acids. The liver makes ketones when glucose supplies are running low. The brain will use ketones as well as glucose. Other tissues run fine on ketones as well. I know I get crazy “ketone burps” when I fast. It’s the same reason an alcoholic’s breath stinks (ketoacidosis), just to a smaller extent (ketosis).
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Nice post. One thing I’m wondering about is what actually signals the body to notch down metabolic rate. I have heard people say that it’s the calories ingested, but I suspect it’s not that simple. I wonder if consumption of muscle protein does this for example. Do you know what triggers it?
Tony
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Great summary Scott
I’d be interested in your comments (and Stephan’s) on this video. I bumped into this guy yesterday at a health food shop he runs in Edinburgh.
http://www.youtube.com/watch?v=3c1lbfhPLeM
He has a big thing about taking honey before bed, so that the fructose is used to refuel the liver and prevent the output of stress hormones which result from low liver glycogen.
It just seems to go against most of what I’ve read about IF…..
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I can attest to the idea that you can fast ad gain muscle at the same time.
Since the beginning of the year, I’ve fasted usually twice per week, sometimes as long as 36 hours, and I time my fasts to conclude after an HIT workout.
I’ve leaned out a lot, and gotten much stronger, in some cases by as much as 200% in terms of what I can lift for three sets of 10. It’s pretty amazing.
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Wow. I’ve never tried any serious fasting but after reading this perhaps it’s something I should consider (especially with all these positive feedback comments).
One question though? Does the hunger never become a distraction to any of you fasters out there? I could imagine going from eating six mini meals a day to nothing ma be quite a shock for my body and trigger hunger pangs.
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Scott, will do a Q&A post to close this series off. Going to include your question.
Jeff, touching on exercise while fasting next week.
Leniza, the brain can run on glucose or ketones. Fatty acids cannot cross the blood-brain barrier, but both glucose and ketones can. I’m assuming (note: assuming!) that in the absence of glucose on a low-carb diet, the body goes through these same stages and after a day or so has stopped using muscle protein to create glucose and begins running much more prominently on ketones. Remember that the body will use aminos to make glucose initially, but eventually uses that process much less to prevent breaking down those all-important muscles. Perhaps someone else can help here.
Stephan, I don’t think I’ve experienced ketone burps. How do you distinguish that from regular burps?
Tony, added to the Q&A post.
Chris, looks interesting. Just from the short video, I can’t argue with his science, but Stephan is probably a better person to give his opinion on that. I’ll see what I can find out and, if anything, will make a post about it.
Tom, I let hunger be my guide. I find since starting fasting a few years back, I am better able to determine real hunger from “it’s time to eat” hunger or “oh look, there’s food present” hunger. Some days, lunch rolls around and I’m just famished…so I eat. That’s the real key to fasting…listening to your body. If you’re hungry, eat. If you’re not, don’t. And I’d advise working into it, not just going cold turkey. Start skipping some of your morning meals and moving that intake later in the day. My IF Success Story has more details on how I pulled it off (link in first paragraph of post).
Cheers
Scott
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Tom:
My attitude about hunger has completely changed. I think it’s important to understand that hunger is a natural physical state that people have been experiencing since the dawn of time. I find that by eating low-carb, high fat, no grains, that hunger is usually pretty mild anyway.
Sometimes I’m hungry and I eat, and other times I ignore it for a while, just like sometimes you’re tired and go to sleep and other times you push through it. The more you’re used to these things, the easier it becomes, and the more natural.
One reason I always work out (brief, high intensity) fasted is that after 5-10 minutes in, my hunger goes away completely and doesn’t return until about 2 hours after the workout. I never eat until the hunger returns.
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Great article, Scott!
I actually have done IF combined with the traditional Atkins style fat fast in between fasting periods, and I have seen huge benefits over IFs with normal (>20% carbs) eating. I will say it is VERY hard to “get things started” in my workouts after day 2, but once I’m going, everything seems OK.
I also monitor bodyfat/lean mass, and while on paper I do seem to lose a few pounds of “lean mass”, it rebounds fairly quickly (3 days or so). Perhaps the “measured lean mass loss” is due to lost muscle and liver glycogen and other fluid loss that occurs when near 0 carb eating? Bodyfat has been measured by an expert with skin calipers (7 site) which basically measures fat content. In this scenario, lean mass is derived from total weight – calculated body fat. For all I know, my internal organs are the “lean mass loss” in this equation, and my guess based on empirical evidence in the gym is that muscle mass is not really affected by this diet.
This seems to make sense, since I’m probably in full ketosis the bulk of the period (which triggers a muscle mass sparing effect, as you eluded to).
I will say that this is not a safe thing to do for protracted periods of time. I limit it to stretches of 3 – 4 days in a row (IF with fat fast), take 3 – 4 days in between, and hit it again, one time. Then, I give myself a few weeks off (or even months). This is definitely a combo where you have to monitor yourself (and keep all your friends and doctor in the loop, too). If I experience wooziness or feel lightheaded, I usually cut the carb fast short and eat some vegetables or something.
I managed to bring my bodyfat from 27% on 1/1/08 to 11% on 3/31/08 using only this cyclical pattern combined with exercise (which had to be tempered at times). I rebounded to only 12% bodyfat (if that) after 2 months of just “making good choices” and not paying any attention to calorie count so much (combined with religiously attending Diablo Crossfit classes).
I will say the biggest benefit of IF (versus sustained restricted calorie diets) is the self-control I build during IF periods. For example, eating a few pieces of fruit after a couple cycles of what I just described translates into eating an entire carton of Ben & Jerry’s ice cream when it comes to the relative pleasure I get from it.
Luckily, I am almost at 10% bodyfat which is my target, so I’ll probably take up more traditional IF just to keep myself on target over the years.
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[...] Forager this week posted a multi-part series analyzing the effects of fasting on the body in terms of energy production, hormones and inflammation. It’s a must read for every cave man considering taking a break from the [...]
[...] A short fast, Wed. exercise, and Wed. calories I started to fast after lunch on Tuesday and didn’t eat again until 8:45 am on Wednesday. This basically amounts to missing one meal, but it felt like a longer fast because in the previous days I had been expending more calories than what I was eating. Missing one meal is pretty easy for me in that I had plenty of energy to go for a bike ride on Tuesday night and to do sprints on Wednesday morning; however my running speed and endurance during my 20-second sprints was down somewhat. I am not tempted by food and my mood stays steady when fasting. I fast to release more growth hormone and for health reasons.  Scott Kustes at http://modernforager.com has some excellent fasting information in a multi-post sequence; you can read the first post by clicking here. [...]
Great stuff! You make reference to fasting during Ramadan. This involves fasting from food and water. Does all the other info apply to fasting from both food and water? How would u say lack of water consumption for that amount of time effects the body?
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Scott,
Very well written overview of the energy systems! I think it’s very important information for people to know as most as so fearful of losing muscle (thanks supplement industry) and also think that there is no fuel so they need carbs right when they wake up, which is not true either as you only need blood sugar…and that can be provided by fats as seen above (thanks cereal indudustry too).
Mike OD
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“While I can’t find anything on this, I don’t think a bit of muscle protein breakdown is necessarily a bad thing, so long as your lifestyle is typically anabolic. I’d think that allowing the muscles to consume worn out proteins allows for better rebuilding of new muscle fibers, clearing out cellular junk.”
M R Eades did a post on that a while back. As I recall, he also said that those junk proteins were also part of the aging process and that IF is good for getting rid of them.
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This is a great article. You did an excellent job of simplifying it so I could understand better! Some things I still have questions on:
1. Is there anything known more about the 18 hour mark of reaching the “fasting” state? Muscle proteins become the chief source of amino acids to fuel gluconeogensis and there is the breakdown of fat stores through lipolysis. But how much of each occurs? After 24 hours of fasting, would lipolysis occur more or would more muscle proteins be used? Would you lose more fat and less muscle proteins if you could make it to a 48 hours fast versus a 24 hour fast?
2. Although this article is about IF, is there anything more about Beyond 2 days: “starvation†state or “long-term fastingâ€. It probably isn’t healthy to fast for too many days but would there be an added benefit to fasting for 3-4 days?
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Hi Scott,
great article again. I’m always sceptical that supposed health experts don’t quite know what they purport to know but everything you say seems so well researched.
In the interests of being a little left field and advancing the debate through going on a tangent. You mentioned how a bird had the same reaction with glucagon that humans and other mammals do in a fasted state. I’ve noticed many similar things too and it got me wondering a little while back how this could be.
Even the apparently obvious concept that we all have eyes that seem to work in a pretty similar way. Maybe we all come from one ancestor that had eyes but I think that at some point one or several species developed eyes and the others found a way of stealing this genetic code.
I made the first point at http://colchambers.blogspot.com/2008/04/can-viruses-do-good.html and then I followed it up at http://colchambers.blogspot.com/2008/05/is-it-possible-to-keep-evolving-without.html.
Funnily enough, since then I found that this process is already understood and has a name. Horizontal Gene transfer http://en.wikipedia.org/wiki/Horizontal_gene_transfer .
So why am I commenting on this if it’s already been discovered. Mainly because I’d never heard of it and I don’t think anyone I know has either. Yet it offers many options and makes the point that maybe we can learn more from other species around us than we realise because they maybe more similar to us than we realise. Maybe we’ve borrowed things from them and don’t even realise.
Like I said this is left field stuff. Just wondered what anyone else though of it.
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Colin, horizontal gene transfer is one possible mechanism. Viruses and bacteria are often the mechanism for making these transfers. Convergent evolution is another possible explanation, whereby the same traits develop two or more times in different branches of the evolutionary tree to accomplish the same or similar tasks.
Cheers
Scott
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[...] I’ve been reading up on a dieting/lifestyle approach called Intermittent Fasting. Sounds old school, doesn’t it? Its the practice of fasting 2-3 days a week. You can do [...]
[...] book Eat Stop Eat. You will certainly find it more understandable! Modern Forager’s series What happens to your Body when you Fast is also worth checking [...]
[...] you’ve been around here for any length of time, you know that I’m a big fan of Intermittent Fasting. This post is intended to lay out my success story since implementing IF as part of my [...]
I don’t like the use of the word ‘Starvation’ that is being used by various people. I know lots of people who have done extended Water fasts.
It is only starvation when the body has used up all its nutrient reserves, and this can take weeks, depending on the person involved. The hunger returns when the nutrient reserves have been depleted. I repeat, this is not Starvation.
Also if nothing else is taken, as you know, the body goes into ketosis, and digests all the stuff we don’t want in our bodies, it protects all its organs and goes into muscle sparing, so it is only in the beginning that it uses some of its muscle, then that is greatly diminished.
If you consume anything else except water according to thirst, then that would make it a starvation diet, as proper ketosis can not be achieved.
On extended fasts, tumours are digested ect by autolysis, and plaque is removed from arteries etc.
So please people, don’t get confused between starving and fasting.
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Ami,
A 3 to 4 day fast would be highly beneficial. However, you need to know what you are doing. And once into proper ketosis you will reach protein sparing, so no need to worry about losing lots of muscle.
For every day you fast, you need to re-feed correctly, this is very important.
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.toc.htm
Read this on-line, a collection of fasting articles by Shelton. It is quite dated but tells you everything you need to know. Although these days people are very toxic.
Hope this helps
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[...] nutrition suppresses the metabolism through various mechanisms. As we learned in the series on the physiology of fasting, the body has ways of dealing with acute food shortages, including recycling amino acids, using [...]
As I read this article I am on my last day of a week-long fast. I believe there is a place for all different lengths of fasting during our lives. I would soon like to do a “complete fast” ie- fast until real hunger returns – often around that 40 day mark. For those interested I’ll mention just a few things from this week. My last week of eating I tried to stick to a pretty heealthy diet and the last two days I cut down on my food intake so I would start my fast with an already “shrunk” stomach. My first day wasn’t too bad. I drank lemon water (just lukewarm water with a bit of fresh squeezed lemon – plain water tates nasty at times while fasting). The afternoon of my second day was a bit rough but I pushed through and by that evening I felt fine. Days 3-5 were fairly easy. Short times of slight hunger would come and go along with slight fatigue. Day 5 was actually really good, but then yesterday (day 6)… well, it started out fine but just after noon I got so weak and tired. I was cold too and so I took a hot shower and laid down and ended up falling asleep for a while. When I finally woke up and got up it took a few minutes to feel normal again but then everything turned around and by the evening I felt fine. Today, my last day, I feel pretty normal. I have a desire to eat (my taste buds want food) but I’m not really hungry and haven’t really been that hungry since day three. Also, I was really thirsty and was loving that lemon water for the first three days and since then my thirst has been minimal. From what I researched elsewhere, folks doing a longer fast don’t really have anymore “bad days” after a week and a half. And after two weeks they get to a point of real energy and a general sense of alertness, etc. up until their body has finished using up other stuff and goes into the real starvation mode. At that point true hunger returns and the faster needs to start eating again. And a note on eating – Be really careful about not overdoing it after fasting for more than 24 hrs. Start with mild things like half a banana or some sweet potato or a fruit smoothie or something. Don’t pig out – I’ve done that before and paid dearly for it with a terrible stomach ache! I hope this might be helpful for some. At least so you know what to expect.
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[...] Let’s first take a look at the definition of Intermittent Fasting provided by Scott over at The Modern Forager: “First things first, let’s define fasting. A simple timeline showing the various states of [...]
I’ve fasted twice in the last 2 years. The first time was a water fast for 8 days, and most recently a juice fast for 5 days. I actually had my fiance do the juice fast with me and we both felt great. Highly recommend it everyone fasts at least 2x per year as well as interminent fasts. ‘Hunger’ is all in the mind, the first 3 days are a struggle for most people; drink plenty of water, take it slow and relax, get fresh air, go for a barefoot walk or light run! Cheers!
David | http://www.barefootrunner.com
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[...] And over at Modern Forager, I found a nice series exploring What Happens To Your Body When You Fast? [...]
[...] Fasting and more and Drs. Eades on Paleo and [...]
nice article.
But like others, i have also experienced weight gain during fasting .
For weight loss the successful formula which worked for me is eating frequent healthy meals, and drink lot of water to drain all toxins which add on weight .i don’t know how to pen it down in term of science.
and also dont get late for or skip breakfast.. it serves as kick start for the fat burning procedure of the body for the day.
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Anju – “dont get late for or skip breakfast.. it serves as kick start for the fat burning procedure of the body for the day.” I can’t tell you how scientifically false this is….oh wait, yes I can. If IF does not work for you, then I always encourage you to do what does work….but there is a HUGE difference between doing IF correctly and just fasting for days. Also if you don’t train for muscle (resistance training) you are not going to have a strong fat burning metabolism in the first place. A combination of IF and weight training will burn the fat.
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Some more info on ketosis.
Yes, your brain can use ketones. But after getting used to glucose for fuel, it needs some time to fire up the ketone machinery. That is why high carb kids actually feel lousy in the morning if they don’t have breakfast. But after a week in ketosis, you will feel much better because the brain burns ketones. And ketones actually provide 28% more energy than glugose (like higher octane fuel in your car). Your hart actually PREFERS ketones to glucose.
When your body is set to use glucose, your body needs 200 grams of glucose to keep your brain and kidneys working when going into ketosis. Your liver is perfectly capable to provide this through gluconeogenesis.
But when your body changes over to using ketones, the need for glucose decreases to 70 grams. So staying in ketosis requires that you keep your carb intake below this level.
Even your muscles will use the ketones in the first few days of ketosis. But, due to muscle protecting considerations, after a week your muscles switch over to burning triglycerides (fat). Training in this ’state’ will increase the number of mitochondria in your muscle cells, thus increasing your energy producing capacity.
Why is ketosis so goor for weightloss? Firstly, gluconeogenesis can make 0,7 grams of glucose out of 1 gram of proteine. The process of gluconeogenesis needs energy to run, and this comes from fat. In using this fat, the ketones are produced. But part of the ketones are wasted in urine and breath. So this whole process is fairly inefficient. How is that for weightloss?
But it gets better. In ketosis your bloodsugar level is very stable. So insuline is not needed in large quantities (some insulin is available all the time). This prevents the hunger pangs. This is supported by the fact that fat and protein in your diet bring quick satiety. And protein helps to further stabalise blood sugar.
But now it get even better. Part of the aging process is the build up of ‘junk-protein’ in your mitochondria. When your body thinks you are starving – because the ketones have been all over the place for some time- it starts looking for ‘disfunctional protein’. So what happens? A process called CMA starts to clear the junk protein from the mitochondria to be burned for glucose. I have even read that ‘fresh cancers’ (when the cancertissue is still soft) are turned into fuel for gluconeogenesis, because yor body recognises the cancer a disfunctional protein. This sounds logically, but for now it is speculative.
And I am not done yet! Another part of aging comes from oxaditive stress on your DNA and cellmembranes. As you may know, digesting of glucose requires oxigen (it actually oxidises when turned into ATP). But burning fat and ketones does NOT require oxigen. So adopting a low carb ketogenic lifestyle reduces the oxidative stress and delayes aging. (heard of calorie restricting diets for mice? I reality the part of diet that was restricted whas the carbs!).
Have you ever heard that human growth hormone decreases with age? It does. And we also know that 80% or more of the growth hormone is produced during sleep. To be precise, during DEEP sleep, one of the sleepfases. And we also know that deep sleep deminishes with age. Is this a coincidence?
But guess what? The ketogenic life style will increase your deep sleep (as part of total sleep) with 25%. This should be enough to keep growth hormone production on ‘youth-level’.
Besides, testosteron is produced out of cholesterol. Gorging on the lovely saturated fats is very good for testosteron production, especially when combined with resistence training.
Did I already mention that cancer cells lack mitochondria and thus need (lots of) glucose for rapid growth? So low carb is low cancer?
Parkinson is the result of a defect glucose metabolism in the brain (diabetis III). Braincells that don’t get energy die. Ketones provide an alternative fuel for the brain- not dependent on the glucose metabolism. Parkinson patients react very well to ketogenic diets. But I say that the ketogenic diet prevents parkinsons disease.
People with a stroke often have brain damage due to hinderd bloodflow. But that is because a glucoseburning brain needs a constant supply of oxigen through the blood. A ketone burning brain doesn’t mind as much when the bloodflow is interrupted for a brief moment- it doesn’t need oxigen! So the ketogenic diet is protective in many ways.
Of course you know that the ketogenic diet decreases triglycerides in the blood and increases HDL cholestrol, thus reducing the risk of cardio vascular disease.
I think I will stop here. Fasting and low carbing is about health and longevity. Oh yes, and do seem to lose weight on it.
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Hi Mike, what do you think of this article?
http://www.soilandhealth.org/02/0201hyglibcat/020127shelton.III/020127.ch31.htm
The whole page is about the great benefits of fasting, which I believe in, but the weight gain part scares me!!!!
Im trying to lose the last 20pounds (Im following paleo kind of diet – eating the real foods, no crap…)
So in order to speed up my fat loss, Im considering to include some fasting days = I wanted to do 3 days water fast, but I dont want to gain it all back (or even more).
Or would it be better to start fasting when I reach my goal weight ???
thanks
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manucia – Using IF is not about extended fasts…..it’s about breaks here and there while still getting in food (quality). Think of it as just compressed eating windows on some days, still focus on getting foods and not just going without anything. If you think fasting is just a quick way to lose weight and do it too much, then yes….the weight comes back. If you do it slow and steady and eat right, you will lose the fat and keep it off. Refer to the IF 101 post on how to go about it (link below) but just remember it’s “Intermittent” Fasting and not extended or excessive fasting we talk about here for the most part.
http://lifespotlight.com/health/2008/02/27/intermittent-fasting-101-how-to-start-part-i/
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Hey, Great post.
Just wondering though about those with a superfast metabolism, who can literally eat anything and they never gain fat? do they go through the same processes energy wise? How is it that they dont store fat?
Thanks!
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Bec, no clue, though I doubt someone with a faster metabolism has any different hormonal functioning as anyone else. The machinery might be running faster, but it’s probably running the same way.
Anyone else know anything about this?
Cheers
Scott
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“I’d think that allowing the muscles to consume worn out proteins allows for better rebuilding of new muscle fibers, clearing out cellular junk.”
http://www.proteinpower.com/drmike/ketones-and-ketosis/ketosis-cleans-our-cells/
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WAY late comment here, but there is an ongoing IF discussion going on at Muscular Development’s Performance NS Forum.
The guy who is selling the crowd on IF uses supplements with Branched-Chain Amino Acids and Essential Amino Acids during his daily fast hours — He uses Purple Wraath. This gets the aminos in your bloodstream so that when your body needs them, it doesn’t strip them from your muscles.
This helps avoid some of the problems you discuss.
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Mike OD Reply:
@Purple – Yes that is one way to go about it for those that are more active and focused on building muscle (vs just weight loss). What’s the link to the thread over there…would love to see the ongoing discussion.
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