Please consider registering

sp_LogInOut Log In sp_Registration Register

Register | Lost password?
Advanced Search

— Forum Scope —

— Match —

— Forum Options —

Minimum search word length is 3 characters - maximum search word length is 84 characters

sp_Feed Topic RSS sp_TopicIcon
The Science Behind The "Low Carb Flu", and How To Regain Your Metabolic Flexibility
sp_BlogLink Read the original blog post
April 3, 2014
4:43 pm

Steves ' post is very intriguing to me also about gluconeogenisis . Steve and I are both drawn to LC for weight and BG issues. All resolved for me. But I manifest completely the opposite problem. If I don't eat a minimal amount of carbohydrates my BG just goes lower and lower and lower. Woke up one day in the 50s. I think my issue helps me have better BG control in the modern world but Steve could survive in the wild hunting and his liver could supply the glucose. I would die unless I could find some carbs. Thoughts? Could you get glucose needs from someones blood? Sorry Steve but in a matter of life and death:-)

April 5, 2014
5:48 pm
Forum Posts: 2045
Member Since:
February 22, 2010
sp_UserOfflineSmall Offline


Thank you for the input!  

It seems like women, in general, can still eat two meals a day -- but many don't seem to do well with the traditional breakfast-skipping 16/8 schedule, and prefer to eat breakfast (even if it's late) and dinner instead.

And no, I don't know why you have trouble maintaining BG levels!  Given that you've got a problem especially in the AM, I'm wondering about hypocortisolism.  

Alas, there's not a lot of glucose even in fresh blood: perhaps a couple teaspoons.  There will be some lactate, particularly if you've just run something down, but I don't believe it's significant.  Fresh liver has some glycogen in it, but fresh meat has very little: perhaps 1.1% by calories.

Since liver has been promoted as a magic carb source, let's do some math.  A human liver weighs about 3.5 pounds (1500g) and contains perhaps 100-150g of glycogen.  So assuming Grok the Hunter can choke down 500g (over a pound) of raw liver after making his kill, he's getting perhaps 30-50g of glycogen from that.

And supermarket beef liver has about 20g of glycogen per 500g (that's 11% carb), so Grok is getting maybe 10-30g extra carbs from "animal starch" if he's lucky enough to have made the kill that day or week.

So yes, the dogma being promoted that "fresh meat has lots of carbs in it compared to supermarket meat" is simply wrong.


June 7, 2014
12:07 am
Neil Barstow

Hi J.
What a great resource. I like your style. Very through, yet easy to read. AND you include the all important references. I am grateful that you take the time.
I'm an almost 60 year old recreational mountainbiker. I discovered low carb via Dr.Mercola's resource and have been eating that way for about 3 weeks. I was very weak on the bike after a few days of my new regime. Good organic/grass fed meat, eggs and veggies, no grains or legumes.
Few beers and glasses if wine (hmm, could that be my downfall).
Anyhoo, thanks to your informative article above, in an attempt to gain metabolic flexbility, I started doing an hour of steady mountainbiking each day and I hope I am starting to feel a bit less weak. At first my legs felt like lead pretty quickly on even an easy hill.
Yesterday was day 5 and I didnt have such painful weak legs, so I am hoping I am reaching the adaptation hump and soon might be over it. I'm eating plenty of varied veg, so I hope my minerals are ok too. I do take a multivit and liposomal vit C.
My question?
Do you have any thoughts about supplementing on exercise days with a carb drink? I like Torq Energy, it does apparently have a balance of glucose and fructose, but the makers assure me it's not the HFCS fructose and should be used up during exercise ratger than stored sine Insulin production is halted during exercise (they say).
Also I guess I'd need to load up a bit the night before, perhaps, maybe also in the morning. Maybe a proten and carb shake (MyProtein Hurricane Evo Velvet Vanilla) might fulfil that need.
What I'd like to do is maintain (actually regain) some sprint capability and not risk damaging my metabolic adaptation by using these carbs to fuel during and before exercise.
I do plan to read Phinneys book for low carb athletes as recolmmended, but I would certainly appreciate knowing anything you night have learned about this please?
Thanks again for maintaining these pages.

June 13, 2014
7:42 pm
Forum Posts: 2045
Member Since:
February 22, 2010
sp_UserOfflineSmall Offline


I'm glad you find my articles useful!

What you'll soon find is that there's often a difference between training and eating for maximum performance and actually achieving maximum performance on race day -- particularly in regards to metabolic flexibility.

In order to increase your metabolic flexibility and your ability to burn fat for energy -- which will increase your baseline "go all day" pace, your maximum pace, and your ability to function while fasted and without a continual supply of food on the trail -- fasted training is far superior, because that's the energy system it stresses. In contrast, you'll achieve maximum single-race performance when you're carbed up and thereby replete with muscle glycogen (though it's best not to eat right before the race…I believe 3-4 hours before should be your last meal).

Similarly, when you're trying to adapt yourself, it's often best to eat low-carb with periodic refeeds so that you're training the fat-burning energy system most of the time. Refeeds are best done right after exercise IMO because your muscles are primed to suck up the glucose and turn it straight into glycogen. Again, there's a difference between training to improve fat-burning and met flex (low-carb) and training for maximum race day performance (however many carbs you need to keep glycogen topped up).

Important: STOP TAKING VITAMIN C. It crushes your body's natural adaptive response to exercise…this has been proven in multiple controlled studies. You won't get stronger, faster, or better as long as you're pounding Vitamin C…the difference is something like 25% vs. 170% improvement with training. Supplemental C has its place when dealing with sickness, but in general you should concentrate on getting it from food.

I'm not a fan of "workout energy"except in dire circumstances, i.e. you're bonking and totally crushed. Even then, little energy is necessary to get you going again (I just take some Halloween candy with me and munch some in the rare event, usually after 4+ hours). As your met flex improves you'll find yourself needing less and less sugar during rides: I've hiked Mt. Whitney fasted!

Let us know how things go for you!


July 11, 2014
1:01 am
Neil Barstow

Hi J,
Thanks for taking the time.
Read your Whitney story, impressive sounds like a great day out. You mentioned that you'd have have eaten if you'd wanted to go faster? Carbs?
I stopped the C, thanks, not read that before but, sure enough, there's compelling evidence out there.
Been biking regularly fasted and doing pretty good at a fairly easy pace. Coffee (with grassfed butter) helps as a start up booster for sure.
Some seem to think one should avoid carb refeeds to stimulate growth hormone, but I do feel keen to down the (MyProtein Hurricane EVO, but shame it has oats in it) recovery drink with whey and some carb. I'll try find something better when I've used it up.
Did one quite hard ride the morning after a risotto dinner and with a pre ride coffee, felt as good as I ever have and really enjoyed it. Maybe I'm "back" ;-).
Its a great resource, thanks
I am enjoying reading The Gnoll Gredo too. Nice work.

July 14, 2014
6:29 pm
Forum Posts: 2045
Member Since:
February 22, 2010
sp_UserOfflineSmall Offline


If I wanted to go faster I'd just have brought some actual food!

You bring up an interesting point about GH: ironically, the best way to get a big GH spike is to train and then not eat anything at all for several hours! Obviously this doesn't stimulate muscle growth, but it dramatically stimulates autophagy -- the process by which old, less-functional cellular machinery is broken down and recycled. This is basically a way to get most of the benefits of a longer fast without having to actually fast a long such, it's not something you do every session, but I believe it's good to do periodically (e.g. once every week or two).

Caffeine boosts the release of fat from fat cells, which is why it helps with fasted exercise...thus the classic coffee+butter (or, even better, coffee+MCT oil) pick-up. And it keeps you in the fasted training fat-burning mode, though you might try omitting the butter/MCT as things improve for you.

Anyway, it sounds like you were somewhat glycogen-depleted from low-carbing. The same thing happened to me: I felt great and had great endurance, but felt "flat" and low on reserves for the extra push, even after several months! The combination of fasted training and being otherwise glycogen-replete should get you going...and when you do decide to go for a PR fully carbed up, you'll probably find yourself doing better than before.

Thanks for following up, and I wish you the best from one mountain biker to another.


July 30, 2014
6:10 am

Update 6 months later - great progress after trying a few different things.

The secret for me was an extended protein-sparing modified fast, and overall focus on very high protein intake. My fasting blood glucose is now 85mg/dL and I've lost a lot of body fat.

For me, and I suspect other people in the stubborn Type 2 diabetes spectrum, the answer may well be both low-carb AND low-fat simultaneously. In other words, get the vast majority of calories from protein.

For the past few months, I've been almost-exclusively eating skinless chicken breast and spinach with a bit of salsa and sea salt for flavor and egg shell for calcium.

Depending on the reference, this is about:
65% protein
15% carb
20% fat

I also eat a slice of calf liver once or twice per week, and add protein powder or nonfat plain greek yogurt as "snacks" between meals. These would skew the actual protein % even higher.

Copious amounts of coffee, but hey, that's practically zero calories... :-)

I've been mostly focusing on weight lifting, and that's helped me get stronger and leaner. "Aerobic" exercises didn't actually seem to have much of an effect for me besides increasing appetite. HIIT primarily seemed to adversely impact my strength and recovery from weight lifting, so I stopped doing that.

I doubt every one would get optimal results from a lifestyle like this, but it could turn out to be just the thing for people with stubborn type-2 (and "pre") diabetes who have not had success with other approaches.

I'm still working on weight loss and am curious to discover whether I get more typical results once my body fat is in the 10% range vs. my current 20% or so, or if my body indeed just insatiably craves protein.

July 30, 2014
6:43 am

To Bea: LOL!!! :-)

FWIW, I also tend towards high hemoglobin and donate blood regularly to keep it in check... So...

But, yeah, my primary source of carbs is gluconeogenesis and my liver doesn't appear to have much trouble keeping up. I did get some "low-carb flu" at first, but I'm pretty well adapted now even though I'm not apparently in ketosis either.

Although I can fast for days without ill effects, I do try to eat protein about 5-6 times per day to make sure that I'm not breaking down unnecessary amounts of lean tissue to create glucose.

It's nice to see that as I lose body fat I actually have a surprisingly good amount of muscle underneath and have recently been getting compliments from women.

If only I'd figured this lifestyle out 20 years ago, lol! :-)

August 12, 2014
9:26 pm
Forum Posts: 2045
Member Since:
February 22, 2010
sp_UserOfflineSmall Offline

(I've been busy with my AHS 2014 presentation…now that AHS is over, I'm going back to many of the comments I didn't previously have time for.)


Congratulations on your success!

HPLFLC is, by necessity, low-calorie -- and if you're in the process of losing a substantial amount of weight you will almost by definition be insulin-sensitive. Remember that protein requirements don't decrease just because you're in energy deficit, so as "calories" decrease, protein should make up a larger percentage of total "calories" even though the absolute amount of protein isn't changing.

Result: energy-restriction diets need to be "high-protein".

The other thing is that energy restriction tends to be stressful, so combining it with high-intensity cardio isn't necessarily the best idea -- as you've found out. Note that you're doing exactly what bodybuilders do when they're cutting fat for contest prep: high-protein, low everything else, keep moving the weight.

So yes, if your goal is to lose weight and maintain muscle mass, you're doing it right! Not everyone copes well with that degree of energy restriction, but if you do, it's quick and effective.


August 26, 2014
6:49 am

Was just reviewing this thread as I'm trying to find the balance for my carb intake now that I'm a lot more active than when I first went paleo (fixed my food and now I have the energy to do more than lay on the couch, go figure). A year ago I was doing 50-70 grams carb a day, but if I do that now ( I bike, weight train, amd I'm learning to play ice hockey) I'm DYING. So it's very activity-specific for me.

Like some of the other females in this thread, I tried IF by not eating breakfast for a while and it made me go off on deranged doughnut binges after I worked out (mmmm...Krispy Kreme....) but if I do big breakfast and dinner I frequently "forget" to eat lunch... Just eat dinner a tad earlier. No mad cravings post-workout, either. So there's one more for your data set.

August 29, 2014
12:16 pm
Forum Posts: 2045
Member Since:
February 22, 2010
sp_UserOfflineSmall Offline


Yes, 50-70 carbs/day plus a lot of physical activity puts you right in the middle of "almost-ketosis", which is a bad place to live. You get the pain of low muscle glycogen without the benefits of actually becoming keto-adapted.

Fortunately, you've probably also discovered that having gone paleo and (at least relatively) LCHF for some time, and having begun exercising, you've also regained some metabolic flexibility -- meaning that you can tolerate more carbs now than you could before! At this point you'll have to experiment and find your own happy medium: increase carbs if performance suffers, decrease carbs if you start gaining fat or feel the blood sugar rollercoaster cranking up.

Thank you for sharing your experiences!


Forum Timezone: America/Los_Angeles

Most Users Ever Online: 183

Currently Online:
5 Guest(s)

Currently Browsing this Page:
1 Guest(s)

Member Stats:

Guest Posters: 1765

Members: 5344

Moderators: 0

Admins: 1

Forum Stats:

Groups: 1

Forums: 2

Topics: 250

Posts: 7103

Administrators: J. Stanton: 2045