Sugar Intolerance: Too Much of a Delicious Thing.

Some people get sick when they eat certain kinds of sugar. Some people get sick when they eat too much of ANY kind of sugar.

So… Is a sugar intolerance causing some of YOUR misery?

What is sugar intolerance?

Pretty woman eating big cubes of sugar.
Is too much sugar ruining YOUR health???

Sugar intolerance can take many forms, from type 2 diabetes to hypoglycemia to bowel problems.

Note that I’m not writing about genetic diseases here. Those are uncommon, and you’d probably know about them before you’d be reading this page.

I’m talking about abuse to our bodies that turn into problems… Abuse that can be prevented to a large degree by changes in your diet.

For people with IBS symptoms, a sugar intolerance can show up as diarrhea, cramping, abdominal pain and gas.

How can sugar intolerance cause IBS symptoms?

Word cloud showing blood sugar related words
The way sugar works in the body is complicated. Eating too much sugar can cause harm to your health in many ways.
© Can Stock Photo

Most people can digest some sugar. But the human body is NOT capable of handling the amount of sugar in the modern diet (see below).

Digestion is pretty complicated. There are enzymes and chemical reactions that happen during digestion that allow your body to absorb the nutrients and sugars in food.

Anything that your body can’t break down and absorb stays in the digestive tract, and exits out the “back door” when you have a bowel movement.

If you eat more sugar than your body can break down and absorb, some of the sugar will stay in your bowels. As this sugar moves through the large intestine, bacteria and yeast feed on it and create a gas buildup. This gas can cause cramping, spasms and pain.

Sugar can draw water into the large intestine or at least prevent it from being absorbed properly (absorbing this water is the large intestine’s main job).

So, excess gas, watery stool (diarrhea), abdominal pain and cramping… I’m betting that sounds familiar to anyone with the diarrhea version of IBS.

Why sugar intolerance is no surprise:

Our ancestors evolved eating a diet of plants, nuts, seeds and meat. They got a small amount of sugar from fruit when it was available. It’s estimated that our ancestors ate less than a pound of sugar a year (some say it was MUCH less). NOW the average person in the “developed world” eats 150 pounds of sugar in a year! So that’s 150 times as much sugar in your average day!

Bag of sugar with a big scoop.
Human beings were never meant to eat SUGAR BY THE BAG. Sugar is in almost everything!
© Can Stock Photo

So our bodies are designed by nature to eat at least 150 times less sugar than we’re eating! Sorry for all the exclamation points, but that’s just too incredible.

Let’s compare that to other foods as an example. What if our ancestors ate 2 pounds of meat a day, but instead we eat 300 pounds of meat a day. Or let’s say our ancestors only at 1/4 pound of meat a day, and now we ate 37 1/2 pounds of meat a day.

Or let’s consider water. If our bodies are designed to take in 1 gallon a day, and instead we drank 150 gallons a day…

A person who did that would be dead in a couple of days or less!

So sugar intolerance MAY just mean our bodies can’t keep up with the ridiculous amount of sugar (and high fructose corn syrup, etc.) we’re eating. It’s more of a surprise that our bodies don’t just fall over!

Sugar is a drug…

Did you know that they used to lock sugar up? Did you know that sugar is highly addictive? Have you ever heard of a “junk food junky?” Well that’s an accurate description of many people (me especially ;).

I sometimes wonder why sugar isn’t a “controlled substance.” Sounds silly right? But people used to use cocaine in soft drinks, and probably would have thought it ridiculous to cut back on cocaine. After all cocaine just makes you feel good and gives you a boost of energy! Hmm… That sounds familiar. Maybe cutting back on sugar isn’t as crazy as it sounds.

When you try to cut back on sugar, the first few days can be horrible. Sugar is highly addictive, and acts like a drug in your system. Once you go through the drug withdrawal symptoms, you’ll probably start feeling a lot better, but for many people it’s a rough time.

It’s probably a good idea to talk to your doctor or a dietitian, to make sure you’re getting enough “complex” carbohydrates.

How to tell if you have a sensitivity to sugar:

One of the best ways to find out about ANY food intolerance is with a food elimination diet. That works very well for fructose intolerance (fruit sugar) and lactose intolerance (milk sugar).

It is more difficult to tell if you have a general sugar intolerance. Sugar is addictive, and when you first stop eating it your body goes into withdrawal!

You’re so busy feeling lousy because of the sugar withdrawal that it’s hard to figure out if sugar is making you sick. You’ll have to wait until sugar withdrawal is completely over before testing with the food elimination diet. When you go to add the sugar back to see if it’s the trouble maker, you’re likely to binge on sugary foods (I’m speaking from experience here.)

Putting together a low sugar, low carb or sugar intolerance diet:

When I first figured out I had some sugar intolerance, I tried the Adkins diet, and felt much better. There have been many other low sugar or low carb diets over the years. Whole books are written about them, and it’s more than I can cover here. But here are some of the famous ones:

The South Beach Diet
The Adkins Diet
The Paleolithic Diet

More recently the FODMAPS diet.

I tried the Paleolithic (or caveman) diet for a while, and it worked very well for me. The idea is that you shouldn’t eat anything you couldn’t get with a spear or from a plant. Basically it means don’t eat what a caveman (or cavewoman ;) didn’t eat. No milk, no corn, no wheat or white flour products, no oats and no beans. All of those items require a mill or cooking before you can eat them.

On the other hand you can eat all the meat fruit and vegetables you want (if you’re trying prevent sugar intolerance symptoms you should be careful of too much fruit).

Over the course of a year, I lost 50 pounds and I felt MUCH BETTER!

But I don’t like to eat vegetables (I’m a vegetable wimp), and so I had trouble getting enough calories. I eventually added corn (i.e. corn chips ;), and rice. Sometimes I “fall off the wagon” and end up eating way too much candy and cookies. I usually feel lousy afterward for a couple of days though.

Other good reasons to kick the sugar habit:

Pudgy woman trying to button jeans that are too small.
Insulin resistance can lead to extra body fat. One more reason to get excess sugar out your diet.

Eating too much sugar makes your body produce a lot of insulin. Insulin moves the sugar into your cells for energy. After a while the cells in your body start to resist the insulin because they’re getting way to much sugar. This is known as “insulin resistance.”

Insulin resistance can lead to weight gain, and can make it VERY difficult to lose weight. Too much body fat can cause hormone problems, heart disease, and a host of other problems.

Being overweight and being insulin resistant often leads to type 2 diabetes (a serious illness). Some doctors are predicting type 2 diabetes will become an epidemic in “developed nations” because of the high level of sugar and simple carbohydrates we eat. People with diabetes usually have to reduce the amount of sugar they eat SO WHY NOT REDUCE IT NOW, BEFORE YOU GET SICK!

Here are specific kinds of sugar intolerance:

Lactose intolerance – when milk products give you problems. The most common sugar intolerance.
Fructose malabsorption – a bad reaction to fruit sugar (aka, how raisins kicked my butt!).

See the Food Intolerance page for other other foods that can cause you trouble.

We cannot load blog data at this time.


  1. Katlin says

    Over the last 6 years (im 20) I am had major problems with fatigue and dizzyness. I got diagnosed with hypoglycemia about 4 years ago and this year with hypothyroidism. I am starting to realize that it is due to a sugar intolerance. I feel sick to my stomach, much more dizzy and fatigued when I eat anything sugary may it be pizza or chocolate, and feel that way for the rest of the day. My whole life its been hard for me to drink sugary drinks and eat things like cookies/ icecream without feeling sick after, but the cravings almost feel worse! IT is a never ending cycle. I love seeing stories like yours and seeing how much better it made you feel to cut sugar out. It gives me some hope! I just wanted to thank you for making this website :) I will use it.

    • says

      Thank you SOOO MUCH for the positive feedback, Katlin. Thank you for sharing your story. I wish you improved health and happiness. – Shawn

  2. Shuree says

    When I binge on cookies, I pay for it the next day, just like a hangover.
    The diarrhea gets so painful that i sometimes throw up.
    Yet, like a fool, i always have a stash of sugar-something nearby.

  3. Ellen says

    Can I just ask – do you have any dark patches anywhere on your body? Neck/Underarms/Groin areas? I hear this is sometimes linked to Insulin Resistance/pre-diabetes. I also suffer with IBS and am worried I may have this.


    • says

      I don’t have any such dark patches myself, but I’ve seen them.

      It sounds like what you’re talking about is something called acanthosis nigricans. I’ve read that this discoloration can be an indication of insulin resistance, or at least the beginnings of it.

      I’ve also read discussions about this being a symptom of other things like PCOS. Dark patches are a GREAT thing to have checked out by your DOC! I know I say that a lot around here, but the Internet is a great way to worry needlessly. A hormone and sugar test may be all you need to ease your fears. You may even find out something that helps your IBS!

  4. tim says

    my lower intestines come alive at night,
    when I’m lying down asleep, about 1-3am the intestines light up and I’m awake, its been years, years.
    When I eat nothing at night of course no reaction half a peaceful night.
    Yep the usual suspects I suppose,
    but i dont drink alcohol much, no coffee at night, keep in minimal.
    I can feel the food hit my bowel.
    I think this has formed a habit in my system, Im thinking of hypnotherapy.

    • says

      Having nights of bad sleep is like a curse. I’m glad I don’t have much problem with that. I wonder what would happen if you had larger lunches and very light evening meals. I have heard some very good things about hypnosis and have a page about it here :. I’ve never tried it myself.

      Tim, if you do try it, I hope you’ll stop back here and let us know how you made out. GOOD LUCK!

  5. Ron says

    Just adding my 2 cents, sugar seems to be my cuase of IBS have had since I was 5 1-2 bouts a week most of my life but when I cut out the sugar specifilly soft drinks really chagnged things for me, its been 6 weeks without a instance of the ” oh my wears the neaerest bathroom ” dont know how long it will last figure if I go 4 months I’m calling it a cure but I was a sugar aholic 3-5 cans a day plus candy bars and other sugars figured at least 200 grams a day now I’m doing about 30 grams a day tops and just really hoping it fixes the problem

  6. Sara says

    Thanks for your info and candor. My mom has been inflicted with IBS since I can remember. I vowed that if I ever found myself in her position, I would demand answers that she never pushed her doctors for.

    Here I am. IBS has slowly become a daily struggle for me and I am working to fix the problem. I just keep cutting things out- artificial sugar, caffeine, sweets, anything spicy or from the pepper family- not necessarily spicy, most dairy (cheese is my weakness). It’s helping, but I think I need to do the Real Deal Elimination diet (ironic because I feel like my everyday diet already is an “Elimination Diet” haha) to get rid of a couple more culprits. I am so desperate to be normal again. Even cheese won’t stop me now!

    Thanks again!

  7. Cori says

    Hi there im new to this forum..but i was wondering if you could possibly shed a light on my situation. I had some blood work done that showed i had insulin resistence. so i slowly cut back my sugar for a week – no refined sugar at all and very little fruit sugar. I then started to notice that i was constipated more so than i usually am. I only usually go once a day. but now i am goin maybe once every two to three days. I started to eat more fruit cause i know sugar draws water into the colon. but i am defeating the purpose of staying away from sugar. now when i eat fruit i notice my stomach bloats and gets very hard. any suggestions would be great thank you so much

    • says

      Hi Cori, Fruit sugar doesn’t agree with a lot of people. See . A lot of times cutting down on carbs (not just sugars) means cutting down on breads, and grains etc. That’s where a lot of people get their fiber. I’d consider talking to your doc about this (a phone call perhaps), cut back on the sugar again, and try some gentle fiber like Metamucil for a few days. Just my humble opinion.

  8. Kelli says

    You mentioned something at the beginning about genetic diseases, we are still trying to understand how this impacts my family. I have been diagnosed coeliac and a couple of nights ago we had roast duck and thai rice GF, and my daughter made a apple crumble GF and went a bit overboard with the sugar. My two girls and I were extremely sick to put it lightly but only just realised two days later how sick we all were. I assumed cross contamination from the Thai rice, but that doesn’t explain my girls. Food poisoning is out because the grand babies ate everything except the apple crumble but my son in law ate the crumble and he was fine so that leaves us with the sugar. I was told that I was fructose intolerant when I was diagnosed coeliac but told it will improve over time that was twelve months ago. I’m having another endoscope today so I should find out if still fructose intolerant in the next few weeks. Any hint or tip that we should be looking at would be greatly appreciated. Kelli

  9. Sharon says

    Whenever I drink orange squash it comes straight back out and its the same for anything sweet like chocolate, fizzy drinks etc. Any ideas on what this could be?

  10. April says

    I’m about 9 weeks pregnant, and having horrible diarrhea as well as nausea, and I just attributed it to normal pregnancy sickness, but I’m realizing it’s worse the day after I’ve had a lot of sugar. Unfortunately I’m craving chocolate and fruit, and everything else just doesn’t sound appetizing. I’m thinking I may just have to flush my system of sugar and see if that helps.

    • says

      April, I’m sorry to hear that it’s miserable for you right now. It’s SUPPOSED to be a happy time. Please make sure to check with the doc before doing anything drastic though! Just in case.


  11. Zombie says

    Hi, I seem to have developed a ‘bad gut/IBS’ over the last two years, needless to say the Drs have not been very helpful. I stopped eating Gluten & dairy but still seem to be getting a lot of gas and uncomfortable gut now and again. I’m now thinking it’s because of sugar as I seem to improve if I cut down on choc biscuits (gluten/diary free) I seem to have such a craving for them with my now boring cups of tea without milk. Anyway what’s confusing me is if I was gluten intolerant how can I drink lager and it doesn’t seem to affect me (not that I’m complaining) but doesn’t lager contain gluten? Also isn’t it full of sugar?

    Thanks, I hope this forum is more helpful than the docs have been.
    Also good luck to everyone.

    • says

      Hi Zombie,

      Sometimes the best way to find any food triggers is to keep a food diary. It’s a pain in the butt, but worth it. Some people have problems with soy and other foods. Eliminating the unnecessary foods just makes life harder with no reason. Not all beer contains gluten, and I’m not sure how much it has, but it’s got to be less than, say, a biscuit.
      It isn’t full of sugar per se, though alcohol can act like a sugar in ways, as can the other simple carbohydrates in a lager.
      Here are some links. I hope you find some help! – Shawn

      The other thing I’ll mention is that for boring tea, etc. there are milk substitutes that are very good. I like almond milk and coconut milk for substitutes for regular milk.

      • Zombie says

        HI Shawn,

        Thank you very much for you reply, I really appreciate it, I’ll have a look at the links. Also my wife bought me Coconut milk which was fine, but the only thing stopping me buying it again is it comes in a minimum 2 pints packs! Which seems very silly to me considering it’s not a product the whole family would use, if the supermarkets stocked it in pints it would be worth buying otherwise it ends up down the sink! Or does it last longer than it says on the box?


        • says

          I don’t really pay attention to the date, but that’s just me. Besides, it doesn’t last long enough to spoil even though I’m the only one that drinks it. I use it with “instant breakfast” or on it’s own, because I got tired of eating eggs for breakfast. I also drink it when I need some quick calories (usually because I’ve been busy and skipped a meal). ALL that being said, when I (rarely) don’t drink it and don’t trust it, I dump it. It’s a waste, but it’s better than no milk to me. – Shawn

      • Zombie says

        Hi again Shawn, I’ve been having GF cereal with coconut milk, it’s v tasty :). One thing I can’t work out is if I get my symptoms which are numerous visits to the loo, and in-between I seem to have uncomfortable feelings of gas in my intestines, but I can’t pass it! This seems to be my biggest irritation, if I go to bed (at bed time) & manage to fall asleep I seem to be able to pass the gas no problem in the morning, it’s just when I’m having my symptoms that I really want to pass wind but it just seems trapped! Thus having to visit the loo just in case!
        One last important question I think would really help me is how long do you think it should (roughly) take after eating something offending that I should have some sort of symptoms? This would REALLY help me pin point the true culprits.
        Finally I have been keeping a food diary, but for example last Saturday 4 days ago I had some cheese & shared a chocolate cake with my daughter & I was fine until yesterday/today, so would you say it’s something else as the cheese & cake were consumed too long ago, or is it possible that 4 days later they would strike?

        This last question I feel is the most important to me as it would really help me work out what the hell is causing this! Sorry for the language.


        • says

          NP on the language, LOL. How long it takes for a food to cause a problem can vary from person to person. It depends on how fast food is moving through your system. For some people it can probably take 4 days or even more (even if they are having bowel movements frequently). It also depends on where the problem becomes active (small intestine, or large or whatever).

          This will seem gross, but one way to find out how long food is taking to move through your system is to eat a bunch of corn. When you see it come out the back end, you’ll know how long that particular journey took. But the amount of time can vary for some people. I wish I could give you a more definite answer.

          Hmmm. I’m thinking that the gas that gets trapped during the day, but comes out at night, might be do to some cramping in the colon. If it pinched off the tube, the gas could get trapped.

          Then maybe as you relax or sleep, your colon relaxes, and lets the gas go.

          • Zombie says

            Thanks again Shawn!
            Out of the tons of sites etc I’ve been on you’re one of the only ones who actually answers sensibly & without daft stories/attempts to make me buy buy stuff. Anyway thank you soo much if you think 4 days is poss then it makes sense

            Thank you,


Please let others know what YOU think!