We’ve all had the experience. We go off our low-carb diet for a while, then decide to get serious and get back on the straight and narrow. We start counting every carb and being good as gold, and suddenly we’re fatigued. We find ourselves puffing and panting just walking out to the mailbox. Old time low-carbers know this will pass, but newbies aren’t so sure. No one told them about this, and all they can think of are all the horror stories they’ve been told about low-carb diets.
I’ve had countless people tell me of how they tried a low-carb diet once and got so tired they had to give it up. They then usually tell me that a low-carb diet just doesn’t work for their bodies. I tell them that if they’ll just hang in there a while, it will all get better, and, in fact, they will have more energy and less fatigue than before they started the diet.
There is an adaptation period that takes place when starting a low-carb diet. Someone who has been on a high-carb diet–the standard American diet, for example–has to metabolize a lot of sugar. All metabolic processes require enzymes to carry them out. Our DNA codes for these enzymes, but we don’t make them unless we need them. And when we do need them it takes a while for them to get brought up to the necessary levels. So, when we’re on a high-carb diet, we’ve got a lot of sugar-metabolizing enzymes kicking around, ready to metabolize sugar. All the sugar-metabolizing pathways are working efficiently.
Suddenly we switch to a low-carb diet. Now we don’t have much sugar to be metabolized–we’ve got fat instead. But our fat metabolizing pathways are kind of rusty. We’ve got plenty of sugar enzymes, but not enough fat enzymes. The body stays put for a bit to see what’s going to happen. Is this just a few hours without carbs or is it a real low-carb diet for sure? Once the body gets serious, signals go to the DNA, which starts coding for the fat-burning enzymes. They are soon made and start to work, and the fatigue goes away because the body can now efficiently metabolize fat, the main fuel on a low-carb diet.
For years it was thought that athletes did better on high-carb diets because whenever they were tested the high-carb diet always performed better than the low-carb, higher-fat diet. That was before trainers understood the low-carb adaptation requirement.
These studies were usually done on young, conditioned people who were normally consuming diets pretty high in carbohydrate. These subjects would then consume high-carb meals for a day, then get on a stationary bicycle and cycle to exhaustion. They would then be fed a diet low in carbohydrates and high in fat for a day or two, then put on the stationary bicycle again. They would fatigue rapidly. Consequently, for years it was thought that low-carb diets reduced endurance, and the idea of carb loading was developed.
Several years back some researchers decided to have their subjects go on low-carb diets for a couple of weeks before the testing and found that when the subjects had the chance to adapt to their low-carb diet, they had better endurance than when they had been adapted to the high-carb diet.
Lt Frederick Schwatka discovered this period of adaptation 130 years ago and wrote about it.
In 1849 Sir John Franklin and a crew of 129 men aboard two ships, the Erebus and the Terror, set out to discover the Northwest Passage. Sir John, his ships, and crew made it to Lancaster Sound in northern Canada, but vanished. It was one of the great mysteries of the time. A number of groups searched without success to locate and perhaps save some of the members of the Franklin expedition, but, alas, no living members were ever found.
One of these search parties was led by Lt. Frederick Schwatka, a West Point graduate and an army physician. Schwatka’s team headed north in 1878 not with hopes of finding any members of Franklin’s party alive, but with the intent oflong-arctic-search-small-blog-size.jpg discovering what happened to them. Schwatka and his team stayed in the far north for two years living with the Inuit. During this time Schwatka lived on “white man’s” food while his supplies lasted and when he could get it replenished, but when that ran out, he and his crew lived as the Inuits, on reindeer, seal, and bear.
During Schwatka’s expedition he kept a dairy, which was packed away in a chest and not discovered until long, long after his death. Once discovered, his diary was published by the Mystic Seaport True Maritime Adventure Series in a book titled The Long Arctic Search.
Schwatka’s diary records the grim daily toil just to stay alive in the hostile climate, not to mention to travel the many miles he did on foot, in small boats, and by dogsled. He also comments throughout on the abundance of game and how easily the Inuit supply themselves and his crew with fresh meat. He noticed the period of adaptation required when he and his team switched from their regular trading-post diet to one solely of meat.

When first thrown wholly upon a diet of reindeer meat, it seems inadequate to properly nourish the system and there is an apparent weakness and inability to perform severe exertive, fatiguing journeys. But this soon passes away in the course of two or three weeks. At first the white man takes to the new diet in too homeopathic a manner, especially if it be raw. However, seal meat which is far more disagreeable with its fishy odor, and bear meat with its strong flavor, seems to have no such temporary debilitating effect upon the economy.

Quaint, but it pretty much describes low-carb adaptation. And it tells us that markedly increasing the fat content of the low-carb diet (seal and bear are much fattier meats than reindeer) decreases the time for the adaptation to take place. Why? Because the increased fat forces the production of ketones, which replace the carbs as a source of energy, especially for the brain.  The more fat, the quicker this conversion takes place, and the less time is spent in the miserable period of low-carb adaptation.
A tip of the hat to Stephen Phinney for putting me onto this book.


  1. Happy Holidays Dr. Eades, i am wondering if you have any conjecture on how a history of alcoholism might affect adaptation to a low carb diet. i have been trying to go low carb and it has been very very TOUGH. i wonder if my 25 years of heavy wiskey/wine consumption may have permanently altered how my body uses fuels or damaged my ability to adapt. i’m interested in your thoughts…thanks…
    Hi Susan–
    Happy Holidays back.
    Your case is interesting because most of the patients I have taken care of who are recovering alcoholics or who have had liver damage from it in the past seem to do better on low-carb diets than any other.
    You may have some liver damage from chronic consumption of alcohol.  I would recommend some alpha lipoic acid and magnesium.  The alpha lipoic acid to help heal the liver, and the magnesium to reduce cravings and make the diet easier to follow.  Also, i would avoid sugar and especially high-fructose corn syrup like death.  Fructose has been shown to cause fatty enlargement of the liver much like what happens with alcohol.
    I hope this helps.

  2. I both agree and disagree. There is an adaptation period, but try as I might, I cannot run long distances when eating low-carb. A few years ago I tried running in a 12k while staying low-carb. My endurance was totally shot and it took me nearly 2 hours to cross the finish line.
    The next year I carb loaded the day before the race and before and during the race. I shaved nearly 25 minutes off my time! I had tons of energy and felt like I could run forever.
    After that experience I decided that while low-carb might be fine for normal life and normal gym workouts, 12k races require a lot of carbs if I want to make good time and feel good.
    I can *walk* 12k on low-carb, but I can’t *run* it.
    Hi Victoria–
    I’ve heard the same from a few others.  I guess it’s a different strokes kind of deal.

  3. I’ve been following your 24-hour IF protocol and understand that lots of ketones are produced on the fasting days. This seems to indicate fat metabolism even though the liver is still supposed to contain adequate glycogen, and I do seem to be gradually losing stored body fat. On IF, will fat-burning enzymes increase even though the feast days contain a fair amount of carbs? I eat five meals on the feast days, but doubt I’m eating double rations.
    Hi athelstan–
    I wouldn’t worry about the loss of fat-burning enzymes on feast days even if you eat a lot of carbs.  It takes the enzymes longer than that to take a powder.
    Keep me posted on your IF.

  4. Very interesting. I’d love to read the book! I just read Stefansson’s story and especially found the treatment for scurvy interesting.
    Hi Cindy–
    I got mine through Amazon.com for about 7$.  I just checked, and there are several there ranging in price from $6 to $24.
    Enjoy.  It was in interesting read.

  5. Hi Dr. Mike,
    I wonder if the higher fatty content of the seal and bear provided not only long chain FA’s but also may provide shorter chain fats which may be used as quick source of energy. I always thought medium chain triglycerides or just coconut oil would be helpful to one starting a low-carb diet to bridge between carbs and fatty acid oxidation. Carntine as well. I wonder if Victoria would do better in her long distance runs with the help of some carnitine. It would be interesting to do some testing such as urine organic acids on those who have problems with low-carb. Maybe we could see where the road block in the biochemistry is/was and fix it.
    Your idea of the short chain fatty acids at the start of a low-carb diet is a good one. (For those who don’t know, short chain fatty acids are taken up directly by the liver in much the same way as carbohydrates are.  Longer chain fatty acids go first into the lymph, then are dumped into the blood stream without first making a pass through the liver.)
    Maybe Victoria will offer to be our test subject.  What about it Victoria? 
    I checked my resources on the fats you mentioned.  I found info on any kind of fat you could imagine except for bear fat.  Seal fat contains a small amount of medium chain fats, but no short chain fats.

  6. Robert,
    I don’t have “problems with low-carb.” I have enough energy day and day and workout to workout. I even require less sleep.
    Low-carb simply doesn’t work for me over a long distance going HARD. On low-carb I’m lucky to be able to run a mile. But after eating high carb for one day I have been known to do up to 5 miles on the treadmill (1 hour).
    My personal theory is that when I am exerting myself that much by body can’t convert the fat into energy fast enough to meet my needs. Carbs are a very easy source of energy and so make endurance runs much easier. I even take carbohydrate gel packs on the run to keep my energy up.
    The race is the one time a year I push myself as hard as I can to see how I do. In fact, last year (after carbing up) I made a new personal best – 1:29:44 for 12k. My goal was to finish in less than an hour thirty, and I just eeked in.
    The race is just a once a year event, but I doubt carnitine alone (which I take) would be able to shave 25 minutes off my time. I haven’t noticed any difference at the gym using carnitine. I’m mostly taking it as a fat loss supplement since I am still above my ideal weight and want to lose a little more body fat.
    I think Robert is suggesting that you try some short to medium chain triglycerides in your low-carb diet before you run to see if the immediate energy they provide improves your endurance.

  7. Dr. Mike,
    As the Archivist of Mystic Seaport (where the original Schwatka journal lives), and a successful low carb dieter I was thrilled to see your post.
    Thank you!
    Hi Kelly–
    My pleasure.  I really enjoyed the book, and I would love to see the original manuscript sometime.  Is it available for public viewing?  Can the book be purchased directly from you guys?  If so, how?
    Thanks for writing.

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