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Why Ketones (and Ketosis) Can Cause Stomach Pain


This is not a “feel-good” post. We are going to talk about some of the not-so-pleasant side effects of transitioning into ketosis, especially looking at why ketones (and transitioning to ketosis, in general) can cause stomach pain. We will also talk about what you can do to solve the issues. Some are practical solutions; others have to do with summoning the mental strength to just deal with a little discomfort to get the rewards and results you want.

If Captain Jack Sparrow were doing the ketogenic diet, he would probably say. “The stomach pain is not the problem… it’s your attitude about the stomach pain which is the problem.”

I’ve been there too. The first time I ever tried exogenous ketones, I was about 16 hours removed from carbohydrates (In-N-Out burger) and I was feeling awful. I thought Perfect Keto would make it all better. I took a heaping scoop of Chocolate and waited 30 minutes. The results? Significant stomach issues, to put it kindly. I thought surely these ketones are bad and I quit my attempt to “go keto” on the spot.


Why Ketosis Causes Stomach Pain

The short answer is dehydration. The process of keto-adaptation is going to dehydrate us. Remember that one purpose of taking exogenous ketones is to speed up keto-adaptation. This means taking ketones will also speed up the side-effects of keto-adaptation.

Why Does Ketosis Dehydrate?

Transitioning to keto means we are moving from using glycogen and carbs to using fat and ketones. There are two reasons this dehydrates us.

1) One of the main inefficiencies with glycogen and carbs is that it must be stored with water. It takes 4 grams of water to store a gram of glycogen.[1] As you run through your glycogen you will lose tons of water (not literally tons but you get the point).

2) High insulin levels (on high carb diets) cause water retention by inhibiting sodium excretion[2]. The keto diet lowers insulin levels, allowing excess fluid to be released.

Add these together, and we have the symptom of stomach pain. Other symptoms will include headaches, lethargy, nausea, brain fog and low motivation.

How to Cure Your Stomach Pain

Back to my story that the first time I tried keto and felt a little discomfort, I gave up immediately. Soon after, I did a little more research and found out that there are simple cures to the symptoms I was feeling. Also, it turns out the symptoms are incredibly common. Nearly everyone who does the ketogenic diet experiences the same symptoms at some point. It is so common that there are literally memes all over the internet about stomach pain when transitioning to ketosis (and they are awesome).

The cures are simple and fall into two broad categories: practical, and mental.

Practical Cures to Stomach Pain

Water – Drink an incredible amount of water. When you feel you have had enough, drink even more.
Salt – Add salt to your foods and drinks wherever possible.
Time – Remember, time takes time.
More Fat – Eating a ton of fat already? Good, eat even more. You don’t want to be low on energy (fat) during the transition.
Slowly Ramp up Exogenous Ketones – Don’t crush a full scoop the very first time like me.

Mental Cures to Stomach Pain

Remind yourself why you are doing this – Isn’t it interesting that all the symptoms we deal with are actually the inverse of the rewards we are seeking? Fatigue will be replaced with energy, brain fog will be replaced with extreme focus, low motivation will be replaced with a heightened sense of well-being.

Remember this is common – keep going, do not worry, and don’t play the victim and give up.

Dig deep – Again, don’t give up at the first slight discomfort like I did. Dealing with some pain is not going to kill you.

It’s remarkable that a little bit of stomach pain has very quick easy fixes, but it caused me to do something irrational, like give up. There is a deeper problem at hand as Captain Jack alluded to – it’s called rationalization.

The Issue Behind the Stomach Issues

Yes ketones and ketosis cause stomach problems, but the real problem is that it causes many people to quit or assume ketosis isn’t for them, or the diet sucks. Enter rationalization. This is the process of taking something irrational (my tummy hurts, therefore I’ll give up) and making it “rational” (this diet is not for me, and perhaps dangerous, and exogenous ketones are bad).

How to Deal With Rationalization Rationally

The first step would be to just notice your internal thought process at work. Instead of looking for simple cures like drinking more water, or adding more salt, or giving it some time, your head might be flying off a cliff. To deal with the problem behind the stomach problems, move down this list:

Remind yourself it’s normal – Everyone who does the ketogenic diet and takes exogenous ketones experiences this. You are unique, but just like everyone else is unique, too.

Don’t give up – Don’t give up because you are experiencing some slight pain and discomfort. On the other side of pain is the reward.

Check your motives – Why do you want to quit? Why did you start this diet in the first place? Does it make sense, or serve you in any way, to bitch about how you feel and why keto doesn’t work? It would probably make the most sense to see what symptoms you have and deal with them appropriately. Don’t hide a bad motive under a seemingly good motive and sabotage yourself.

Why Ketones and Ketosis Can Cause Stomach Pain


Back to my story, I ended up trying ketosis again and this time I didn’t give up or panic about stomach pain. I drank tons of water and upped the fat and salt and gave myself space to feel a little uncomfortable.

The results are now the side effects I feel are tremendous energy, focus, and well-being. I still occasionally do feel stomach pain, and it is a reminder that ketosis is in action, and I should probably hydrate. 🙂

If you are going to do a strict ketogenic diet and take exogenous ketones, here’s what you can expect:

Initial Negative Side Effects

  • Dehydration
  • Stomach Pain
  • Brain-Fog
  • Low Motivation
  • Irritability

Eventual Positive Side Effects

  • Energy
  • Focus
  • Well-Being
  • Longevity
  • Low Hunger
  • Better Sleep

Do all the practical cures mentioned above – Water, salt, time, fat, and mental strength.

This may be harsh but everyone wants to “go keto” until it’s time to do what it takes. If you want it, get your butt up and make it happen. Use your pain to make a smart adjustment and take yourself to new heights and inspire others.


57 thoughts on “Why Ketones (and Ketosis) Can Cause Stomach Pain

  1. I am going to be blatantly honest about the fact that I don’t need you to tell me to suck it up……but I do know that some people need that. I am doing this for the first time……and that is extremely relevant because I have been obese for most of my life to the tune of over 180kg, but in the last 7 years I finally won the weight battle and lost 100kg……not by doing this…..however!……I have learnt a lot over my 100kg journey and am continually open to learning and trying what I learn so I can pass onto others the results…..and I can honestly say that this info has been extremely helpful….THANKYOU! ??

  2. I found your article both funny and very helpful. I have been following the keto lifestyle for 9 months. Just when I thought I had it all figured out…I start having stomach cramps, gas, bloating etc. What I neglected to realize is that hydration needs to be a huge priority! I got lazy. Well I can’t have it both ways. Looking after myself is work and I’m the only one that can do it. No excuses! Thx for the pep talk again!

  3. Hi,
    I appreciated your insights in the article. I have been eating keto for 3 weeks and have been in ketosis almost from the beginning. I use the sticks and my level is the 2nd to 3rd color on the spectrum. I athave lost 17 pounds in 3 weeks and I know some of that is water. I ordered a 5 day special supply of the exogenous supplements from a facebook keto guy. My question is..if I am eating under 25 carbs a day and counting macros, and losing about 3-4 pounds a week, do I need the extra ketone supplements? Also, I have not had any stomach pain, just have to take fiber to keep my insides moving properly. Do most people get stomach pain from the supplements? I am planning on stretching the 5 day supply to 10 days, because with a normal diet I do get stomach issues and so far with keto eating I don’t. Thanks for any answers you might have for me. I need to lose at least 30 more pounds.

    1. Hey Lisa, awesome to hear about your success so far! To answer your first question – no you do not NEED to use ketone supplements – they are another tool in the tool box to help with other things such as workouts, during fasts, getting back to utilizing ketones for fuel after a slip up, etc. In terms of the stomach pain, it just depends on how sensitive your gut is – some people have to start off with smaller doses and work their way up whereas others are perfectly fine with a few doses a day.

  4. Thank you so much for this very helpful blog. I started getting worried why every time I eat Avocados my stomach would hurt so bad, thanks to your very good and clear explanation all my worries are gone and upping water and salt is in my future 🙂

  5. What exactly is “stomach pain”? Because while I don’t have pain all the time, some nights I have had it so bad, I’ve thrown up everything I ate, even if it was several hours earlier. I am starting to think it’s one particular kind of fat or one particular food. It only happens at night after dinner, and is not always accompanied by nausea or the runs. I don’t know how to approach figuring out what this is.

  6. I feel better after reading this. I wasn’t sure if it was a reaction to dairy or what was going on but my stomach is in knots. I will definitely up my water. As far as salt I feel like there is a fair amount in the foods I have been eating, should I still add in more? Thanks!

    1. 1/8 tsp of sea salt in your water will DO wonders I assure you and you can’t taste the small amount in a litre but your body will thank you. Salt can be your friend and when in Keto, or sodium , potassium and magnesium levels can drop significantly. Keep these minerals up will also help alleviate if not elimninate the “keto flu”. You do need to take caution and not over do it especially with the Potassium too much of that is NOT a good thing. Magnesium also helps with mood as well. You can add it in tablets or a couple good epsom salt baths a week can also do the trick as it is absorbed thru the skin as well

  7. Ive been keto adapted now for approx 3 months, and have just started getting severe stomach cramps
    When i started keto i adjusted quite well, after i realised the water intake needed increasing, initially i used hydralyte tablets just to get me through
    But the last few months have been great- except recently…. cramps arr so severe they keep me up at night
    Any suggestions?

    1. If proper water and salt intake isn’t helping you may want to see a doctor to maybe check for possible gallbladder issues or other GI problems.

  8. I have been on a ketogenic diet before. I was in a moderate state of ketosis and I remember feeling all of these things and the benefits after. It only lasted a few days at the most and after that I felt better than I had in a long time. Plus I lost 45 lbs.(over 6 months) Getting ready to start again and I already feel sick to my stomach. Worth it. Thanks for the article.

  9. Thanks for the encouragement and the post. This is my first attempt at Keto. I felt great getting up and on the treadmill (first time ever) drank a Keto coffee and boom my stomach hurts. I needed this post to push through and not give up ??

    1. Hi krisanne,
      BEST salt to use is pink Himalayan salt than sea salt.
      Salt to AVOID is normal white table salt with or without iodine.
      Keep it up!

  10. This post saved me last night! The past two night I’ve woken with terrible cramps and a feeling of light headedness. I knew I wasn’t hungry but couldn’t think why I was having them. I began to slightly panic thinking that the ketogenic process wasn’t good for my body. But then I googled online and came across this article. I was dehydrated that’s all! Lol I made myself 500ml of spring water and added a couple pinches of Himalayan pink salt into it and downed it. The stomach cramps went away immediately and I began to feel really good. I fell back to sleep and woke up feeling refreshed.
    Thank you!

    1. Thank you for your story and this information. I started the keto diet about five days ago and was at work last night and had such severe stomach cramps and vomiting. I stuck it out for most of my 12 hour shift but had to leave early. I wish I would’ve had this information then but now I do. Thanks again!

  11. Hi I have started taking the chocolate ketones and the MCT powder every day for the last three days. I have had a terrible runny stomach. I did start off with half scoop on both – should I cut these back even more? Particularly the MCT? I’m not sure if it’s the ketones or a virus as I eat or drink and have the runs straight after. I’m also on keto eating

    1. Hey Tracy, I would cut back on one of them and see how you feel. Introducing two things at once that your body isn’t used to can cause some GI distress for some people. I would just choose one for now, use about 1/3 scoop and work your way up and see how you feel.

  12. I think the info here is great, but don’t forget that some people out there may have undiagnosed GI or other issues that can cause this kind of pain. If this is persistent, despite an increase in water (most ppl don’t drink even in the ballpark of what they need), salt, fats, etc… and persists after some amount of time… a person might have an outside issue they need to see a doctor about.

    On the other hand, I have found some exogenous ketone products to be more gentle than others—experiment! (And remember that supplementation may not be for everyone!)

  13. So good article, thanks. I would like to ask, when fasting from dinner to lunch, is it ok to take ketones, coco oil and MCT in the morning or should I wait till lunch? Thx!

    1. Hi Muniba
      If you are trying to be strict with fasting for the amazing cell autophagy benefits, you do NOT want to have those in the morning as that will break your fast. Water, sparkling water, black coffee, green tea are all good while fasting. Anything that has calories(any oils, MCT powder) will break a fast. Exogenous ketones are ok while fasting as long as they DONT have calories. Keep it up!

  14. Hi, Today is my second day and all night I could not sleep due to the cramps, was doubting myslef what I have put myself in. But after reading this I feel motivated and just have to push a few more days. I am drinking alot of water. Is it going to go soon? How many days can it continue to the max. Thank you for this article!

  15. Amazing I thought the same as most of the other Keto-ers. Ready to give up feeling rotten to the core not worth all the effort and scarred to faint very tired and or worse. So this really helps to stay focused for another day.drinking water is going on all day today and will reassess.
    My question is what about the Bullett Coffee is that another tool to lose weight or just a very tasty cup of coffee?
    Ellen de Man

  16. Thanks for the tips! I’m just starting keto and have been experiencing stomach uncomfort . I will try your tips. Thanks!

  17. Thank you. This was very helpful. I gave up last month because I thought my symptoms were a stomach virus. I got back on track and having the same exact symptoms. Decided it was the keto drinks so googled it and found this page. YES , I am definitely dehydrated and not eating enough fat. Will change that starting today!
    Also, I am down a pant size and so thrilled!

  18. Thanks for this post! I needed that! I’m a bit confused because I’m two months in on Keto and I’ve lost 15 pounds. I never did have the keto flu at the beginning, but just this week I’ve had a stomach ache and it’s really thrown me. Nice to know it’s normal. I’ll persevere. It’s so worth it. After counting calories for 10 years to lose my last 10 lbs of baby weight, I ended up gaining 15 more. It didn’t work. This isn’t effortless, but at least it works!

  19. Another tip — I add 1/8 teaspoon of salt and some lemon juice to 32 oz. of water–this adds sodium and potassium. I drink 3 or 4 jugs a day of that. If you are drinking straight water you’ll eventually leach out all your electrolytes and you’ll feel like you are going to pass out several times a day.

  20. Excellent article ..made me feel a lot better .it’s my 6th day on keto and I was experiencing some stomach pain since I know what to do about it.thank you

  21. I have been on the keto journey for 4 weeks today. I went through the keto flu, found out I really needed electrolytes which I’m taking Ultima 2 times a day. Staying pretty darn close to a 70% 25% 5% macro count everyday. But I am still getting weird pains in my stomach, more like an ache. Still having problems with getting lightheaded and dizzy. What am I doing wrong. ????. Any advice is appreciated.

  22. This site is godsend for keto info. Now back on topic. I believe the author is mainly talking about the transition period in the beginning associated with keto flu. I passed through hell week but had prepared mentally for it. In 2 months I’m down 13 kilos about 30 lbs. in my 2nd month I ve started having pain right under my left ribcage. Like something is going numb in there or sometimes sharp pain. Burping and passing wind eased the pain. I would wake up at night with pain. I got scared and had an ultrasound. They checked everything gallbladder liver bile kidney and everything was in great shape and was such a relief as I was worried for stones. The pain is still here. It’s on and off. If it continues and it’s not bearable with added attention to electrolyte intake I will look closer to the intestines with medical help. I still have ways to go on keto and I hope I get over this hurdle.

  23. I’m in my 3rd week of my keto plan. I’ve lost 21lbs. Started to feel nausea after eating in the afternoon. Tried drinking more water, protein drink, protein water. Doesnt seem to help. Also been having severe charlie horse pain in my abdomen. Tonight I cut up a few kiwi and ate them. Crossing my fingers it helps.

  24. Hi l just want to thank you for the information l have been worried that the diet was’nt for me as l have been getting bad stomach pains for a while l must addmit l dont drink that much water but after reading this l will be, thanks ahain

  25. I’m in my 3 weeks keto diet under Diet ,I felt now a very painful stomach upset like I have gastro intestinal problems ,I lose 7lbs,I like it but the feelings ,I really want to give up.Thank you.I will follow your advice.Liz

  26. I need help with this Keto diet. Been off all carbs except for green veggies for almost two months and have hardly lost more than 5 pounds. I fast from dinner til lunch or sometimes even til late afternoon. Usually have cheese and pork rinds (limited portions) and then dinner which is a good combo of protein and veggies (green beans/kale/broccoli/cauliflower) and a salad with very low carb dressing. How am I NOT losing weight? I’d like to see some results 🙂

  27. Today is day 20 on keto and I have had bad bad bad stomach pains every evening for the last two weeks. I drink over a gallon of water a day, I’m very good with my water intake. I asked this same thing on a Facebook group and I was told to drink less water, which I did yesterday and today and today is the worst my stomach pains have been and they came way earlier in the day. I am getting super discouraged because it happening every single day for weeks and it hurts so bad I feel like I can’t breathe. I will add more salt to my diet and hope for the best.

  28. I was having intense pain and everything was running right through me . Also burning when I urinated . I looked it up and read this post and immediately started guzzling water and Himalayian sea salt and within 15-20 minutes things were better . Thank you so much for the information. I am tough and determined and stick to a plan no matter what . I’ve lost 20 lbs in 2 weeks . Just push through it , it’s worth it and your self well being will kick in . I’m having no problems fasting and not really hungry . Also taking magnesium supplements .

  29. I’ve been doing Keto/carnivore for 3 weeks. The stomach pain the past 2 weeks is now unbearable and interrupting my life. I don’t have the runs just severe stomach pain to where I cannot stand up straight. What can I do? I’m about to quit this diet.

    1. Hi Bryan, some people may experience a minor gastrointestinal (GI) discomfort due to their body newly being exposed to ketones. It’s wise to limit additional salt intake and drink more water.

  30. I am in to about 4 weeks with the keto diet, and my stomach has been hurting me so bad, I don’t have a gallbladder so I wonder if I’m having problems breaking down fat? But I’m still trying to hang in there, reading everybody’s post gives me a little more incentive! thank you!

  31. Thank God I found you all!! I’m 3 weeks on keto and the past week the stomach cramps, mostly when I try to lay down at night, are horrendous. I’ve had 3 kids and at 61 yrs. I am no stranger to pain but these cramps wipe me out and I feel bruised. I will up the water and pray for a night’s sleep.

  32. When I would get stomach cramps I would just drink a class of Gatorade 0 help with sodium and water but dont drink to much, gotta mix it up with water and such. I also find drinking straid ice tea (no sugar) enjoyable.

  33. Thank you! I had 6lb to lose and started the Keto diet.I felt flu like and felt like a zombie for few days then I had serious stomach pain that I could not believe I thought it was time for Emergency Department because the pain was so burning and upset feeling, but decided to drink mineral concentrate and sea salt in warm water at first it all came right back up .. I wonder if I’m seriously dehydrated because that seemed so odd. Anyhow feel much better

  34. I’m in need od some advice, I having serious stomach ache as well but I’m in my 4th week and so disheartened iv managed to gain weight, I seem to be the only one that this has happened to.. The problem is I don’t want to quit keto but thinking this isn’t for me.. I’m scared to up my fat content just in case I put on more.. HELP

    1. Hi Jane, sorry to read that you’re experiencing serious stomach ache! Drink more water and add salt to your diet. Eat more fat to keep your energy level up and take supplements gradually to give your body time to adjust.

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