Metabolism and ketosis
Since posting the piece on ketone bodies and their causing breathalyzer problems I’ve had enough comments and emails to make me realize that there are probably many people unsure of what ketones really are, where they come from and why. Let’s take a look at the goals and priorities of our metabolic system to see what happens. Fear not, I’m going to try to keep the biochemistry to a minimum.
The primary goal of our metabolic system is to provide fuels in the amounts needed at the times needed to keep us alive and functioning. As long as we’ve got plenty of food, the metabolic systems busies itself with allocating it to the right places and storing what’s left over. In a society such as ours, there is usually too much food so the metabolic system has to deal with it in amounts and configurations that it wasn’t really designed to handle, leading to all kinds of problems. But that’s a story for another day.
If you read any medical school biochemistry textbook, you’ll find a section devoted to what happens metabolically during starvation. If you read these sections with a knowing eye, you’ll realize that everything discussed as happening during starvation happens during carbohydrate restriction as well. There have been a few papers published recently showing the same thing: the metabolism of carb restriction = the metabolism of starvation. I would maintain, however, based on my study of the Paleolithic diet, that starvation and carb restriction are simply the polar ends of a continuum, and that carb restriction was the norm for most of our existence as upright walking beings on this planet, making the metabolism of what biochemistry textbook authors call starvation the ‘normal’ metabolism.
So, bearing in mind that carb restriction and starvation are opposite ends of the same stick and that what applies to one applies to the other, let’s look at how it all works. I’ll explain it from a starvation perspective, but all the mechanisms work the same for a carb-restricted diet.
During starvation the primary goal of the metabolic system is to provide enough glucose to the brain and other tissues (the red blood cells, certain kidney cells, and others) that absolutely require glucose to function. Which makes sense if you think about it. You’re a Paleolithic man or woman, you’re starving, you’ve got to find food, you need a brain, red blood cells, etc. to do it. You’ve got to be alert, quick on your feet, and not focused on how hungry you are.
If you’re not eating or if you’re on a low-carbohydrate diet, where does this glucose come from?
If you’re starving, glucose comes mainly from one place, and that is from the body’s protein reservoir: muscle. A little can come from stored fat, but not from the fatty acids themselves. Although glucose can be converted to fat, the reaction can’t go the other way. Fat is stored as a triglyceride, which is three fatty acids hooked on to a glycerol molecule. The glycerol molecule is a three-carbon structure that, when freed from the attached fatty acids, can combine with another glycerol molecule to make glucose. Thus a starving person can get a little glucose from the fat that is released from the fat cells, but not nearly enough. The lion’s share has to come from muscle that breaks down into amino acids, several of which can be converted by the liver into glucose. (There are a few other minor sources of glucose conversion: the Cori cycle, for example, but these are not major sources, so we’ll leave them for another, more technical, discussion.)
But the breakdown of muscle creates another problem, namely, that (in Paleolithic times and before) survival was dependent upon our being able to hunt down other animals and/or forage for plant foods. It makes it tough to do this if a lot of muscle is being converted into glucose and your muscle mass is dwindling.
The metabolic system is then presented with two problems: 1) getting glucose for the glucose-dependent tissues; and 2) maintaining as much muscle mass as possible to allow hunting and foraging to continue.
Early on, the metabolic system doesn’t know that the starvation is going to go on for a day or for a week or two weeks. At first it plunders the muscle to get its sugar. And remember from a past post that a normal blood sugar represents only about a teaspoon of sugar dissolved in the entire blood volume, so keeping the blood sugar normal for a day or so doesn’t require a whole lot of muscular sacrifice. If we figure that an average person requires about 200 grams of sugar per day to meet all the needs of the glucose-dependent tissues, we’re looking at maybe a third of a pound of muscle per day, which isn’t all that big a deal over the first day. But we wouldn’t want it to continue at that rate. If we could reduce that amount and allow our muscle mass to last as long as possible, it would be a big help.
The metabolic system could solve its problem by a coming up with a way to reduce the glucose-dependent tissues’ need for glucose so that the protein could be spared as long as possible.
Ketones to the rescue.
The liver requires energy to convert the protein to glucose. The energy comes from fat. As the liver breaks down the fat to release its energy to power gluconeogenesis, the conversion of protein to sugar, it produces ketones as a byproduct. And what a byproduct they are. Ketones are basically water soluble (meaning they dissolve in blood) fats that are a source of energy for many tissues including the muscles, brain and heart. In fact, ketones act as a stand in for sugar in the brain. Although ketones can’t totally replace all the sugar required by the brain, they can replace a pretty good chunk of it. By reducing the body’s need for sugar, less protein is required, allowing the muscle mass (the protein reservoir) to last a lot longer before it is depleted. And ketones are the preferred fuel for the heart, making that organ operate at about 28 percent greater efficiency.
Fat is the perfect fuel. Part of it provides energy to the liver so that the liver can convert protein to glucose. The unusable part of the fat then converts to ketones, which reduce the need for glucose and spare the muscle in the process.
If, instead of starving, you’re following a low-carb diet, it gets even better. The protein you eat is converted to glucose instead of the protein in your muscles. If you keep the carbs low enough so that the liver still has to make some sugar, then you will be in fat-burning mode while maintaining your muscle mass, the best of all worlds. How low is low enough? Well, when the ketosis process is humming along nicely and the brain and other tissues have converted to ketones for fuel, the requirement for glucose drops to about 120-130 gm per day. If you keep your carbs below that at, say, 60 grams per day, you’re liver will have to produce at least 60-70 grams of glucose to make up the deficit, so you will generate ketones that entire time.
So, on a low-carb diet you can feast and starve all at the same time. Is it any wonder it’s so effective for weight loss?
Hello,
I have been eating only fat and protein for the last two months. I started with low calories and gradually increased them in the form of cheese, fish, eggs and chicken, the first couple of days I ate about 400-600 calories from meat and fish predominantly. In the subsequent days I slowly increased them to 1800 and at day 15 I added more. I began eating oil, butter and virgin oil. I am consuming close to 0 carbohydrates, no vegetables either. At the moment I am consuming about 3500 calories. I am a ‘precision’ person and have been monitoring my ketosis since the very first day. In the beginning ketosis was very high, almost the darkest on the scale. I couldn’t help, but notice that when I increased the calories after 2300 ketosis became lighter. I am still in a constant ketosis, sometimes I measure it 2-3 times a day. It is just not as high as in the beginning, but the first square that indicates it. I am wondering what does this mean? Does it mean that my body is using the calories from fat and protein more efficiently, since I am burning less ketones? Or that my body uses the ketones in some other way. Other than that I am tremendously pleased with myself, since I started I feel better and my PCOS disappeared on one of my ovaries, my moods stabilized and I began ovulating. So it is a great thing really for sure. thanx a lot! great blog!
It more than likely means you are adapting to ketones, and that your tissues are using them more for fuel, thus spilling them less in the urine.
Can someone from this thread please show me how to make a diet consisting of 70% fat? I can’t seem to figure it out on my own.
I had much success with a low carb diet a decade ago. I lost 60 lbs in a year. 10 years later, the weight has crept back on.
I am trying to have a go at it again but I just cannot seem to shed the weight. I bounce up and down between a 5lb range. I am steadily passing keytones and I am regularly in the “small” to “moderate” range. I am exercising 30 minutes a day (15 bike / 15 Stairs). I am not using whimpy settings either.
I have 2 cups of black coffee in the am. I have a low carb protein shake in the afternoon. Anything else is water but I might have 2-3 diet sodas a week.
I had a blood work done before I started, but now I am thinking of getting a more in-depth insulin test done.
Thoughts?
You’re a decade older, a decade more insulin resistant, a decade more glucose intolerant and have added a decade’s worth of metabolic damage. All of these processes, and others I can’t think of off the top of my head, combine to make weight loss much more difficult on any kind of diet when compared to how that same diet worked a decade earlier. Take a look at the posts on this blog on why low-carb is harder the second time around. Even though it is more difficult the second time around, the low-carb diet is still the most effective and quickest way to lose weight and improve health even a decade later.
[...] Metabolism and Ketosis [...]
[...] drugs). There is also feud if a ketogenic diet causes flesh wasting. Some believe it does, and other experts are austere that it does not. The some-more flesh mass we have, a some-more fit your metabolism, [...]
[...] There is also disagreement if the ketogenic diet causes muscle wasting. Some believe it does, and other experts are adamant that it does not. The more muscle mass you have, the more efficient your metabolism, [...]
[...] drugs). There is also feud if a ketogenic diet causes flesh wasting. Some believe it does, and other experts are austere that it does not. The some-more flesh mass we have, a some-more fit your metabolism, [...]
Great article. Thank you so much for this.
I have a question. I am currently in my fifth day of ketosis and have been losing weight fairly rapidly. I am taking fiber supplements since the last time I tried a low carb diet (about 10 years ago) I was extremely constipated.
The fiber supplements seem to work… there’s no blood in my stool and there is slight constipation, but it is manageable; however, my last bowel movement had an ammonia smell… hence I have been digging around trying to get an answer.
The most common answer is that ammonia smelling stools is a result of nitrogen not being metabolized correctly, which means the food I am eating is not being digested properly resulting in a putrefication (sp?) of undigested food that ends up in the colon >>> this gives off the smell of ammonia. The “cause” seems to be fiber deficiency. Obviously that means the fix is to inject more fiber.
I am NOT medically savvy at all, so I apologize if I have butchered the terminology.
Thanks again for this!
Blaine
@Blaine. I’d try lowering the amount of protein you are eating and increase the fat. You shouldn’t need the fiber if you eat enough fat.
Check this link
http://www.phlaunt.com/lowcarb/19063904.php
Hi Blaine
Increase the amount of water you drink as the number one remedy to constipation. Do not drink more than 500 ml of water in a 1/2 hour time frame, too much to fast can kill you. You should be drinking from 3 – 4 liters daily. You can ad fiber such a phycillium to your diet. I use 12 tsp with 150 ml of cold water. The bacteria in your stomach will adjust as you continue to eat low carbohydrate. As far as I’m concerned I have the best bowel movements when I eat low carbohydrate. when i consumer high carbohydrates I’m telling you I pay dearly, painful, and just horrible smell. Fiber includes vegetables so as long as you are including good veggies in your low carbohydrate diet you should have plenty of fiber.
Enjoy I’m just a low carbohydrate lover no credentials.
live love laugh
Ha ha… that’s not “inject” more fiber… that’s INJEST more fiber.
Not really, it’s “ingest”
True again…
[...] of Dr. Mike Eades. You still don't have to go low carb but you will understand it without any fear. The Blog of Michael R. Eades, M.D. » Metabolism and ketosis Female, 5'3", 46, Starting weight: 160lbs. Current weight: 136lbs. Read this: The [...]
The human body is designed to thrive in the absence of dietary carbohydrates, or food altogether (i.e. starvation). The first few days without carbohydrates (or food) do lead to some minor losses in muscle mass (between 60-84 grams, or 2-3 ounces), as the body catabolizes amino acids from your muscle tissue to fuel its shift from using glucose for energy to ketones. But by the third day, the body is fully capable of providing for nearly all of its energy needs through the production of ketones, a by-product from the metabolizing of your stored fats. From this point onward, your body only needs a tiny amount of glucose, just 18-24 grams (1/2 to 1 ounce) daily.
[...] *sigh* This is BS, right? Dr Eades has a nice blog on ketosis and metabolism The Blog of Michael R. Eades, M.D. » Metabolism and ketosis (and my opinion of that piece of writing is that they are trying to make people sick so that they [...]
I have been on this diet through a local dr. I am a vegetarian. I have followed it to the letter. I have kept a food diary and have taken my supplements and had all of my water. I have been on the program for 2 weeks and have actually gained weight. They told me it is because I am a vegatarian. My test strip said I am in Ketosis. What is your opinion?
I know my comment is late but I hope this helps. In my opinion, if you are consuming fats such as coconut oil and butter ( if you consume butter ) and it is a larege part of your diet AND you are consuming enough protein you should be fine. However, you might want to have your thyroid checked. This diet will tell you what, and if, anything is out of place if you let it. If you have thyroid problems, you definitely will want to cut out soy in your diet…assuming that you are eating soy.
I am a kidney cancer survivor of 6 years. I had a right radical nephrectomy and portions of my left lung removed. Having only one remaining kidney should I have concern follow a low carb high protein diet? My blood sugar is normal, kidney and liver functions as well. I am 56 yrs old, very active until 2 years ago when I had a total knee replacement in order to remain active. In my case the total knee had the opposite result and I am much less active, have had to give up officiating football and cut back on golf. As such I have gained almost 40 lbs. I have always been a large person, 6’3″ 260 most of my life, but now push 300 lbs. I went on weight watchers with no positive results. 10 days on a low carb regimen, stay hydrated and I am down 9 lbs., but am I potentially doing more harm than good?
There is no evidence that the protein content of a typical low-carb diet causes problems in those with normally functioning kidneys. In your case, you have only one kidney, but presumably that kidney is functioning fine, so you shouldn’t have a problem. Having said that, though, you should check with your own physician, who knows you best, before making any kind of radical dietary change.
Just to give a little support to Dr. Eades comment, my mom had to go on dialysis and was encourage to eat lots of protein. There is a link to some information on the ketogenic diet can help treat if not reverse kidney damaage. I will post it and look forward to Dr. Eades comment.
Here’s a link on the ketogenic diet for kidney therapy:
http://www.msnbc.msn.com/id/42689095/ns/health/t/low-carb-high-fat-diet-could-replace-dialysis/
[...] read the book yet. I think the better link to read on this topic on the above blog is this: The Blog of Michael R. Eades, M.D. » Metabolism and ketosis I think that recent research has shown that the idea that protein is converted into glucose is [...]
[...] strongly recommend reading Dr. Mike Eades excellent post about “Metabolism and Ketosis” for more [...]
[...] Can someone explain the efficiency of ketosis and muscle retention Can someone explain the efficiency of ketosis and muscle retention compared to some one doing lo calorie diet. How does a person on low cal do lipolisys compared to someone in ketosis? I want to think there the same, but to lose fat on low cal you have to use your glycogen stores then burn fat. Where in ketosis you always burn fat. It's in the transition on low cal that you lose muscle. I read it has to do somthing about the liver not making glucose in presence of ketones. So it uses fat for glucose Here's a link if interested The Blog of Michael R. Eades, M.D. » Metabolism and ketosis [...]