What is Ketosis?

The Kreb Cycle

Ketosis is a metabolic function that occurs with low-carb diets.  Instead of using carbohydrates for energy, the body will turn to its own fat stores and break them down for energy instead.  This usually results in a rapid loss of fat (and pounds) that sounds great in theory, but in practice is a bit more dangerous. Our bodies use ketosis the same way a car uses the fake donut tire in your trunk.  It's enough to get you to the garage, but it's not meant to be driven on indefinitely.  In the same way, ketosis is a by-product of the body's reaction during a time of starvation that allows it to keep functioning until it can get to its next carbohydrate. What is a carbohydrate?  Pretty much anything that's not fat and not protein.  So if you get rid of oils, butter, meats, fish, and poultry, pretty much everything else is a carbohydrate.  That includes super-healthy carbohydrates like salads and not-so-healthy carbohydrates like a cheese pizza. There are a lot of advocates for low-carb diets.  I think what they're advocating is reckless and unsustainable.  Yes, you'll get a quick hit of weight loss and the weight loss will come from fat, but you have to put your body into starvation mode to allow it to trigger ketosis.  This will almost certainly mean a nasty weight rebound when you inevitably stop eating the low-carb meals the diet prescribes.  I'm not the only one against a ketonic diet. I've also had the "pleasure" of experiencing the effects of a long-term ketonic diet.  It happened when I was pregnant.  Due to hormones going crazy during my first trimester (a genetic trait I have), I was diagnosed with something called hyperemesis.  That's just a fancy word for morning sickness to the factor of 100.  I could barely eat anything, was constantly throwing up, and if it wasn't for frequent IV bags, would have died.  (Famed author Charlotte Bronte did, in fact, die of hyperemesis.) During the worst phase, when I wasn't receiving good care, I wound up in an acute care clinic and couldn't remember my name when asked.  In the back of my mind I said to myself, "This really isn't good."  My husband looked on horrified when he realized I truly couldn't remember.  Luckily we changed doctors, finally got good care, and they stabilized me somewhat.  At week 20 of my pregnancy, I could finally keep most of my food down.  To give you some perspective, I ate a full meal on September 15 and my next full meal wasn't until Thanksgiving Day.  I was truly thankful. Symptoms of ketosis include:
  • urine and breath will smell different (ketones are being released)
  • nausea and vomiting
  • confusion
  • weakness or fatigue
  • shortness of breath
  • in severe cases, death, which means it's no longer a symptom.
Do you really want to go down this path to lose a few pounds? Is that worth it to you?  I hope when you're reading about these diets and considering them that you'll find this post instead and consider another route.  For those who say it's safe if you're only in a "little bit of ketosis," I say you're playing with fire and you should stop. For people who are actually struggling with a ketotic diet, if you're having an epically bad day, please just eat a piece of whole grain bread.  You'll feel better in about 15 minutes.  As always, consult with a doctor before you begin any diet and go ahead and ask them their opinion of ketotic diets.  I bet you'll get a similar answer to mine. Cheers, Lisa

About Lisa Johnson

Lisa Johnson here. I've been a personal trainer since 1997, a Pilates instructor since 1998 and the owner of Modern Pilates since 1999. I'm hoping to give you some good ideas to get or stay in shape with a healthy dose of humor and reality. Thanks for joining me.

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21 Responses to What is Ketosis?

  1. Justin May 2, 2012 at 4:52 pm #

    Are the Paleo Diet or Eat Stop Eat considered Ketogenic diets?

  2. Lisa Johnson May 2, 2012 at 8:39 pm #

    Justin it depends on the ratio of carbs that you eat in relation to fats & protein. If you’re ever not sure go to the local pharmacy and ask for ketone sticks. You pee on them and they tell you where you are. They’re cheap and they’ll let you know where you are. :-)

  3. Justin May 3, 2012 at 1:43 pm #

    Thank you, Lisa!

  4. Phil Earnhardt June 1, 2012 at 1:09 pm #

    I’ve recently learned quite a bit about ketosis metabolism recently. Several nuggets:

    1. “ketosis” is a broad word describing a whole range of metabolic phenomenon. Ketosis first starts with the liver kicking into high gear. Your urine may smell a bit funny (same smell as some get when eating asparagus), and your breath may smell a bit fruity. Part of this first stage of ketosis is acetone in the blood, which is removed from the body through several pathways including breathing. There are some anecdotal reports of police breathalyzers recording false positives.

    2. The changes in liver chemistry cue the individual cells (primarily muscle cells) to alter their own chemistry. The cells get better at burning fats, and they also start breaking down the fat molecules themselves. This time of transition is colloquially known as the “Atkins flu”.

    3. The longer-chain fat molecules are hydrophobic and are more difficult to transport to cells. As the molecules are broken down, they become more hydrophilic. The smallest ketones are small enough and have the correct chemistry to pass through the blood-brain barrier. These small molecules can be used as a source of energy for the brain. Besides explaining how individuals on a low-carb diet continue to have a functional brain, ketogenic diets hold the promise of helping some chronic diseases. One example: the brains of Alzheimer’s patients become less adept at burning glucose, but they don’t lose the ability to burn ketones.

    4. The transition of ketosis blood chemistry being dominated by the liver to being dominated by the breakdown of molecules by the individual muscle cells is crucial. Before the muscle cells adapt, that initial period is highly stressful on the liver. The first-stage chemical by-products detected by the ketone sticks (and, anecdotally, the breathalyzers) start to disappear.

    I am most impressed by the research and publications by the Duke Health researchers on Atkins-style diets in the last decade. http://www.dukehealth.org/health_library/news/7598 from 2004 is a good start. They checked out everything Atkins from top to bottom. Duke Researcher Westman partnered with Harvard/Standford/MIT researcher Stephen D. Phinney (MD and PhD) to write the new Atkins book in 2010. Phinney has now published “The Art and Science of Low Carbohydrate Living” (2011) and “The Art and Science of Low Carbohydrate Performance” (2012). For those interested in a current fact-based discussion of low carb diets, those three books are about as good as it gets.

    My final recommendation of a source is Steve Gibson’s podcasts about low-carb diets:
    http://www.grc.com/health/lowcarb-podcasts.htm . The bad news is that Steve has no background (and certainly no certifications) as a dietician. He’s a computer programmer and uber-geek — a guy who still codes his PC programs in assembler — and one of the best thinkers I’ve ever met. Steve has gathered facts, scrupulously consulted with his doctor, and has reported on what he’s finding in that research and in his own body. His podcast coverage is great: besides great audio of the shows, he provides written transcripts of the podcasts.

    Lisa is right on: any sort of diet like this should be done with caution. The diet is stressful (particularly at first) on the liver and other organs. They’re not for everybody, and they should be done under the guidance of your doctor. On the other side, people are seeing some remarkable results on their blood chemistry and their athletic performance.

  5. Lisa Johnson June 3, 2012 at 3:09 pm #

    Phil, thanks so much for the perspective. I’ll definitely be clicking around to your different sources. L–

  6. SkittleS1982 December 9, 2012 at 8:20 pm #

    I think the wrong time to do a low carb diet or calorie restricting diet is when pregnant. I’ve done a LOT of reasearch on low carb diets and they sound fine to me. I’d like to see your sources. Thank you.

  7. Lisa Johnson December 9, 2012 at 9:29 pm #

    well, yes I would definitely agree the wrong time to do a low carb diet would be during pregnancy. But low carb is not how we are naturally programmed to eat. Please don’t confuse low carb with low starch … I’m all for ditching processed, starchy foods and the veggies that have less nutritional value to them (say a white potato vs. a sweet potato). Carbs encompass everything that isn’t a protein or a fat … pretty much everything else is a carb.

  8. MarkW January 22, 2013 at 11:11 am #

    I think it’s rather irresponsible to broad brush ketosis, declaring that low-carb diets are “reckless and unsustainable.” There is mounting evidence everyday that shows that excess sugar, especially fructose, is the primary driving force in the obesity epidemic. Refined carbohydrates, found in most all processed foods, break down into sugar. This excessive sugar impacts insulin levels and its resistance. It’s the underlying factor of nearly every chronic disease out there. History and demographics have shown that cultures and races that have incorporated low-carb diets into their way of life actually have better health profiles than our “fast food, drive-thru” Americana mentality. Starving yourself for two months during a pregnancy as a result of being ill shouldn’t be the basis of determining whether a body in the state of “nutritional” ketosis is reckless. If your readers would adopt a diet eliminating all sugars and refined carbs, cutting out all high fructose corn syrup and hydrogenated oil, BUT eating 7 oz of lean protein daily, with unlimited vegetables having low carb content (essentially, placing themselves into a nutritional ketosis state), they’d all be much healthier. It’s inevitable that fruit will migrate into that healthy eating routine, throwing the person in and out of ketosis, but as long as they are eating nutritionally, being in a state of ketosis shouldn’t doesn’t matter. That is why a healthy body allows the process to occur. Human cells can live on both glucose and ketones, depending upon the current state of diet. Remember, the human race actually foraged for thier food before McDonald’s came along.

  9. Lisa Johnson January 27, 2013 at 4:56 pm #

    Mark you are making the classic mistake of not understanding what a carb actually is. There are three forms of macronutrients, fats, protein and carbohydrates. Fruits and vegetables are carbs, so is bread … they are ALL carbs. It’s one of the things that drives me nuts when people talk about cutting out carbs. You’re not. You’re cutting out starches and processed foods, totally different thing. And yes, grains are immediately converted to sugar in the body and might as well be considered the same as sugar. The UC Davis Lecture, which you can find on YouTube, “Sugar: The Bitter Truth” talks about this in a really easy to understand way.

    So you can eliminate starches and sugars, not eliminate carbs and NOT be in ketosis. Perhaps you should do a bit more research. :-) L–

  10. geen March 28, 2013 at 6:53 pm #

    I like what you’ve written and even agree with most of it except the suggestion to eat a piece of whole grain bread. Whole grain bread today’s nothing but poison! Please so some research on the dangers of wheat and glutton.

    If you need to take yourself out of the ketosis state instead of wheat, get your carbs through fruits and vegetables. It’s much healthier.

  11. Lisa Johnson March 29, 2013 at 10:26 am #

    Geen, I agree that fruits & vegetables are more nutritious than whole grains, but for a quick fix from a “bonk” a piece of bread will go a long way. I think poison is perhaps too strong a word. Yes, I’m familiar with the Wheat Belly guy and his “frankenwheat” theory and I’m very familiar with the Paleo folks talking quite strongly about how evil grains are … I think if you talk to the average dietitian however (I mean an RD) that they would say whole grains are good for the digestive system, in fact a new study came out just this morning saying we need 30 grams of fiber a day … it’s harder to get that from veggies, a bit easier from whole grains.

  12. Bekky smith March 31, 2013 at 1:09 pm #

    This is one of the most ignorant descriptions of ketosis I have ever read.

  13. Lisa Johnson March 31, 2013 at 5:11 pm #

    hmm, well Bekky, normally I’d just delete this comment as it’s negative without being constructive in any way. But I’m actually going to respond. I’ve talked about this extensively with two different dietitians and I’ve read extensively about ketosis from a slew of medical journals and as this post said I’ve experienced ketosis (granted at the severe end of the spectrum). So … unless you can site some sources that come from studies that have been properly vetted disagreeing with what I’m saying please feel free to stop visiting my blog. :-) Cheers L–

  14. The barringer April 24, 2013 at 8:48 pm #

    So do you think that just a moderate fat intake with a relatively low carb (not a no-carb) intake is appropriate for a healthy alround diet? Because it seems to me that a balanced diet of real non-processed food just makes sense. If you think about what our grandparents ate at our age( which is almost 30) and what they were eating in those days and even before the industrial revolution. I am not looking for fast results on wieght loss but just a healthy way of losing wieght,( granted an I would take an easier route if it didn’t mean sacrificing my health now and in the long term) any suggestions? I excersise almost daily and I run for 30 mins along with core excersises 5 days of the week( been doing that for about a month now).

  15. Lisa Johnson May 3, 2013 at 10:06 pm #

    Barringer … you seem to be doing just fine and yes I agree w/ a “balanced diet of real non-processed food” focus on fruits and veggies, lean proteins and minimize starches and minimize sugar. You’ll get there eventually. You running sounds great, throw in some fartleks (intervals) to goose your metabolism a little. Cheers, L–

  16. Vaughn June 7, 2013 at 10:39 am #

    Lisa, I listened to your interview on The Smarter Science of Slim podcast and decided to check out your site and ran across this post. I’ve been a proponent of the low carb lifestyle for quite some time. In total I’ve lost about 80lbs over the past few years and have felt fantastic. I’m much happier and enjoy life more that I’m not tired and sluggish all the time. I’m pretty close to being in the same shape I was in during my college years 15 years ago. My cholesterol, blood pressure and other health markers are within normal/healthy ranges. I started this journey when I was diagnosed with pre-diabetes, high blood pressure and severe obesity. My family has joined in as well. Both of my kids play multiple sports and are A-B students in school.

    When I talk to people about what I’m doing for health I like to avoid the term low-carb because of all the connotations people have about this. I’m not sure why, but people have assumed that low carb is just about eating pounds of bacon at a time. As I thought about what I ate I discovered that it’s best described as a diet of natural whole foods. Low carb DOES NOT mean “no” carb. My carbs come from green leafy vegetables, some fruits and some nuts. I limit the amount of starchy vegetables so that I can keep my insulin levels stable. The fruits and vegetables include a good amount of fiber and other nutrients and I enjoy as much as I like.

    I view processed foods and sugar as the enemy. Nearly everything in a package has added sugar, HFCS, transfat and other nasty things. I want no part of that stuff. After doing a cursory glance at your site, this doesn’t seem much different from what you write about. The biggest differences may be in the importance of whole grains and dietary fat in the diet. Fat has been an important component in my diet. Avocados, coconut oil and fat from pastured meats have been my friend on this journey leaving me full and satisfied. Whole grains tend to make me sleepy after I eat them.

    During this time I have been in some state of ketosis. As I mentioned my energy level has been through the roof and cognition better than it has been in years. In this post it sounds like you might be confusing ketosis with ketoacidosis. These are very different instances. Ketoacidosis occurs in extreme circumstances of people with liver/kidney issues and type 1 diabetics and some pregnancy complications like you experienced. Ketoacidosis is very dangerous, limited to extreme cases and not generally associated with low carb diets. Ketosis on the other hand has been shown to healthy and helpful.

    For a different perspective here are couple links below for you to check out. You might also look at some of the research by Gary Taubes, Jeff Volek, Stephen Phinney and others. Also, Jimmy Moore is a podcaster that has been documenting his journey with nutritional ketosis that is interesting as well. I’d love to hear what you think after doing some more research.




  17. Lisa Johnson June 7, 2013 at 12:05 pm #

    Hi Vaughn,

    It doesn’t seem that we’re that different at all actually and yes I do know there is a difference between ketosis and ketoacidosis and yes that IS what happened to me during pregnancy. Although my understanding is that it’s just a continuum, I was pegged all the way to the worst end of it when I was preggers.

    That said, I’ve seen plenty of people on “low carb” diets (I don’t like the term either) complaining about headaches and fuzzy thinking and feeling groggy. Some of that might by their system clearing the junk of sugar addiction and processed food crap but some of it is also ketosis at too high a level. I had a rather extensive interview about ketosis diets with David Grotto, a pretty awesome guy who is very well educated, an RD, written a bunch of books, etc. (also just a really nice guy) and his argument is this something that can be reasonably sustained for a long period of time? That is a question each individual has to answer for themselves and clearly for you the answer is yes.

    And you are getting enough carbs or those nasty symptoms would start creeping in. :-) As you said, nuts, fruits and veggies are all carbs or mixed-carb foods and used as fuel by your body.

    For my part I’ve recently met with a nutritionist for my own minor health issue and we have found it’s clearing up nicely by adding a few whole grains back into my diet (we’re talking about 2 oz. of homemade whole grain bread or one small serving of oatmeal here). For me, this is working well and honestly was a surprise because I didn’t think it would work.

    My ultimate point is … each person has to judge for themselves what is best for them according to what their lifestyle is and what their bodies tell them. Thanks for stopping by and for the thoughtful reply.

    Here’s the David Grotto interview … http://www.lisajohnsonfitness.com/what-is-ketosis-talking-with-a-top-nutritionist/



  18. Vaughn June 8, 2013 at 10:23 am #

    Thanks for your response Lisa. You’re absolutely right that we all need to find out what’s best for our bodies. I’m happy that you were able to find a way to address your nutritional issues. My hope is that whether vegan, vegetarian, ornish, paleo, low carb or low fat, we can come together and agree that the processed food industry and pharma do not have our best interest in mind and get the word out about this. We can also band together to speak out about HFCS and transfat instead of focusing so much on the differences in philosophy. At the end of the day, we want people to live longer, healthier and happier lives.

    I look forward to communicating with you more.

  19. Lisa Johnson June 8, 2013 at 8:49 pm #

    Thanks so much Vaughn, you rock. :-)

  20. David August 15, 2015 at 9:17 pm #

    Damn shame that people would intentionally make themselves sick as a way to drop weight.!!! Instead of simply eating the foods that we were built to eat as humans..

  21. Dale Robinson-Gervais July 24, 2017 at 12:21 pm #

    Hi Lisa,
    Please accept my criticism as constructive. I think there are a lot of people out there with an axe to grind at every turn and I am not one of them. It does concern me that you have taken such a hard line view of ketosis while actually discussing ketoacidosis. You didn’t really leave it at “each person must judge for themselves” in your initial discussion as you suggested to Vaughn. As a person attempting a responsible fitness blog, you would be wise to be more careful how you lay out your arguments. While each of us is an experiment of one, that “one” (as you so unfortunately discovered) can dip into extreme states while not representing the norm. Yours is a cautionary tale, for certain, but should not serve as a scientific view of the subject of nutritional ketosis. Vaughn deserves a lot of credit for setting your readers straight.

    Please take the time to look at Mercola’s work in Fat For Fuel and Perlmutter’s’s work in his books Wheat Belly and Brain Maker. It could change your thinking and help you to help others, which I assume is part of your mission in this lifetime.


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