What Does Low Carb Mean?

Many say low-carbohydrate eating controls diabetes. Others say such diets are unhealthy or impractical. But what does “low-carb” mean? If you want low-carb, what can you eat, and how much? Let’s see.


I’ll admit that, right now, I don’t have the answers. But I do have time to read books and search the Internet, and Diabetes Self-Management hired me to do it. So hopefully, over the next few weeks, I can give you some useful information.

You might find some of this old news, but I’d like to start with the basics. First, scientifically speaking, what are carbohydrates? According to Wikipedia, a carbohydrate is an “organic compound that consists only of carbon, hydrogen, and oxygen,” usually with two hydrogen atoms to one oxygen atom. So basically, they’re carbon and water.

Kind of incredible what Nature can do with those simple building blocks. Plants make carbs by combining carbon dioxide and water with the help of energy from the sun. The sun is the source of the energy carbs provide. All plant foods except seeds are mostly or completely carbohydrate.

In biology, carbohydrates are also called saccharides. There are four kinds. Two of them, monosaccharides and disaccharides, are usually called sugars. (“Saccharide” comes from the Greek word for sugar.) Most mono- and disaccharides have chemical names ending in “-ose,” like lactose (milk sugar), glucose, and sucrose (table sugar.)

Other carbs are called “polysaccharides,” more often called “starches.” The body can easily break starches down into sugars for energy. If you hold a piece of bread in your mouth, it becomes sweeter and sweeter. That’s because saliva enzymes are turning the starch into glucose.

The last types of carb are the “oligosaccharides” which make up much of the fiber we get in vegetables and other plant foods.

Carbs in the body
Mono- and disaccharides are many people’s main source of fuel. However, various food scientists say carbohydrates are not vital, because the body, except for the nerves, can get its fuel from protein and fats. The nervous system can’t use fat for energy, but can use ketones, which come from the breakdown of protein. That’s why some people can stay healthy without any carbs at all, as the Eskimos did when eating their native diet, and as some low-carb fanatics do now.

After being digested, most carbs (except for fiber) turn into glucose and are used for fuel. Some can’t be used, usually because cells already have all the fuel they need. The unused glucose can be converted into starch (glycogen) and stored for times of high energy use, like a long run or skipped meal. Or it can be converted into fat for long-term storage in case of famine.

Certain carbs do have other functions. One is deoxyribose, which is a major component of our bodies’ genetic material, DNA. Some oligosaccharides appear to help sperm and ova come together for reproduction. Fiber has numerous benefits, which I documented here.

Carbs and diabetes
Since the main function of carbohydrates is to provide glucose for fuel, when you eat them, your blood glucose will go up temporarily. Everyone’s does; it’s not open to question. But how much it goes up, and how long it stays up, varies according to many factors. The biggest factor, by far, is diabetes.

In a person without diabetes or prediabetes, insulin will rush into the blood at the first sign of carbohydrates. As the body absorbs carbs, the insulin will grab the glucose and take it to the cells, to be used as fuel or stored. So blood glucose typically will not go above 140 milligrams per deciliter (mg/dl).

But a person with diabetes has less insulin, and what they have doesn’t work well, because of insulin resistance in the cells. Something is wrong in one or more parts of the insulin system. Without effective insulin, glucose stays in the blood until the kidneys excrete it in the urine. So glucose levels can go above 200 mg/dl, sometimes far higher, and they can stay there for a long time.

Injecting premeal insulin helps, but it doesn’t solve the problem of insulin resistance, and it increases the risk of low blood glucose (hypoglycemia), which also causes damage. Other medicines also help, but none can really manage the high glucose levels that many carbs produce.

High glucose levels after eating are the cause of most of the complications of diabetes. Those high glucose levels damage nerves and blood vessels. Insulin-producing beta cells also start to die off when glucose stays above 110 mg/dl. This is probably why diabetes progresses over time. Fewer healthy beta cells mean less effective insulin will be produced.

You can see numerous studies documenting the effects of glucose levels above 140 mg/dl on Jenny Ruhl’s site Blood Sugar 101.

Now, since carbohydrates turn into glucose, and people with diabetes don’t have the effective insulin to use the glucose, and too much glucose makes us sick, we probably should consume less of them. But that’s a lot easier said than done, or even understood.

As I mentioned, most plant foods are largely made of carbs. Do we have to avoid breads, fruits, vegetables, everything that grows? Are we supposed to eat nothing but meat? That can’t be healthy for us, for the animals, or for the planet. So what ARE we supposed to do?

Dozens of low-carb diets have been recommended. But there are so many of them, and so many questions.

First, how much carbohydrate is low-carb? Next week I’ll go over various recommendations for how much carbohydrate to eat, and what types. Then we can talk about the best ways to consume fewer carbs, and how to decide for yourself if you want to do that.

It would really help the discussion to hear what your experiences have been, and what knowledge you have gained. Thank you for contributing.

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  • Mark


    I was diagnosed with TYpe 2 diabetes on 9/14/11. At that time, my blood sugar was measured at over 500. Since then, I have adopted a primal diet, based upon the books by Mark Sisson. This is a high fat (70%) low carb (10%) and protein (20%) diet. I now have a fasting blood glucose level of 80, which would make me “normal” and non-diabetic. I do not take any druggs, just diet and exercise. The diet consists of berries, some nuts, grass-fed meats (or any red meat), vegetables and , in my case, dairy. I have lost over 80 pounds on this diet and reversed my gout, diabetes, blood pressure and arthritis issues. I don’t believe that the low-carb lifestyle works for all individuals, but I believe that anyone with Type 2 diabetes should seriously entertain the use of a low-carb diet with there metformin for blood sugar control.

  • calgarydiabetic

    Some sort of carb limitation in type 2 IMHO is essential for good blood sugar control.

    Used to be I could eat a 33 % diet carbs ,protein and fat. But that diet caused the diabetes to progress and now the less carbs the better in spite of a lot of medication including 3 types of insulin.

    Whole grains make little difference to the blood sugar spike. So I have eliminated all grains (except ground flax seed, flour, rice, potato, and all food including low fat yogurt that are high in starch.

  • jim snell

    calgarydiabetic makes excellent comments.

    I agree on the comments but I would add that in order to eact white rice, potatoes et all, I practice tight portion control and fried in olive oil/fat stops the spikes otherwise vertical.

  • Joe

    A low carb diet is not a no carb diet. I eat low carb everyday. I do not eat just meat, I do enjoy bacon and sausage once in a while, but I do try to stay away for processed meat. I eat green leafy vegetables, sprouts, broccoli, mushrooms, green peppers, and the list goes on and on. I even eat black berries, blueberries, walnuts, raw almonds in small amounts. I do not eat for the most part is processed foods, grains, and starchy vegetables. After dropping my body weight from 260 to 180 lbs my AC1 levels were 6.2 (not bad). I figured out I was eating to much protein and my body was turning the extra in to sugar. I was also still trying to follow my doctor advice and eat low fat which was not helping. I cut my protein and add fat (mostly not saturated) and my AC1 dropped to 4.2. My cholesterol level are at 75 LDL and 60 HDL. I am off all medicines (including my blood pressure, cholesterol, and diabetes). For information on low carb I like Dr. Richard K. Bernstein books, Atkins books, primal diet by Mark Sisson, and diabetic articles by David Mendosa(espeical his low carb articals).

  • calgarydiabetic

    I think a good definition of low carb would be the amount of carbs per day that you can safely eat and maintain your blood sugar in the normal range at all times.

    This may vary from diabetic to diabetic depending on the severity of the disease and medication from 150 grams to next to none. Although eating 100% sauerkraut could be workable ( I will try for a week and see). But barring the un-american. Whole grains, potato, rice, cookies, starch in low fat dairy products should be eliminated.

  • calgarydiabetic

    P.S to the above

    While keeping the blood sugar in the normal range at all times will usually suffice.

    Sometimes carbs have to be cut further to permit weight loss.

    Also lipids will usually improve quite a bit when you get your BS in the normal range but further cuts maybe needed to satisfy this need.

  • Onoosh

    I am also a fan of Dr. Bernstein, David Mendosa (his photography is also great!) and Jenny Ruhl. Jenny’s writing was instrumental in directing me, and my wonderful doctor and nurse, to test for, and confirm, my LADA or “Type 1.5” diabetes when I was originally diagnosed as a Type 2.

    I eat no more than 75 grams of carbohydrate per day, most of it consisting of leafy and cruciferous vegetables, with cheese, one serving of fish–a concession I made as a vegetarian because my food choices were so limited–a very little fruit at breakfast, a little soy, and some butter. My husband, who is a fan of the Mediterranean diet, uses only olive oil to cook. I eat a few nuts and use a few of my carbs every day for some very dark (90% cocoa) chocolate. I sometimes steal a sip of my husband’s European beer. 😉

    My only grain is a couple of Kavli brand crackers per day: any other starches, grains or legumes send my BG soaring.

    I have learned, through trial, error and close BG monitoring, what works for me and what doesn’t. That, I think, will vary between individuals. But my fasting BGs–absent situational stresses like a ride on the interstate, an illness in the family, or pain from a ready-to-be replaced hip–are generally in the 75 to 85 range, with my 2-hour pp numbers usually under 120.

    I take 250 mg of Metformin morning and night, and 8 units of Levemir, plus a snack, at bedtime. My hypos, if any, are mild and manageable. I know I won’t be able to control the course of my disease, or prevent my body from destroying its own beta cells, forever, but I want to do as much as I can on my own, while I can.

    I encourage everyone out there to experiment, monitor, record, and simply pay close attention to their own processes. And make low-carb a game, to see how low you can go, within reason–Dr. Bernstein says he hasn’t eaten a piece of fruit in 25 years!–and take control of your life.

    And let’s keep encouraging one another! 🙂

  • fingertips

    I agree with most of you. I just finished an intense 6 week program that helped me to better understand my diabetic circumstances. I found out that I still produced significant amounts of insulin but my body is moderately insulin resistant. So I came off of glipizide. I continued Metformin. I began a moderate exercise regimen. My BS has flat lined at 100 & I lost 30lbs.
    I also found out that I can’t handle more than 2 servings of starch daily & that I really should eat those for either breakfast or lunch. The only meat I ate was fish, no fried foods whatsoever, no dairy, only 2oz of olive oil (& 2 fish oil capsules), & unlimited fruits & vegetables.
    I plan to continue this exercise with additional tweeks for the next few months.
    I need to check out the authors that you recommend. I read the books by Dr Fuhrman, Dr Hyman, and Dr Oz; that where I got the idea to try this exercise.

  • David Spero RN

    Thank you all for these great comments. I would like to know more about what you DO eat to replace those starches and sugars. I think that’s what I’m writing about next week.

  • Onoosh


    To reiterate, and list a couple of things I forgot in my first post, I eat eggs and “Egg Beaters;” cheese (full fat) and butter; cream in my coffee; a variety of veggies–non-starchy, and in controlled amounts–a (very) little amount of fruit; a bit of tofu, sardines, kippers or sometimes salmon; olive oil and a controlled amount of dark chocolate. A couple of Kavli brand crackers a day are my only grains.

    I drink a lot of fluids, because I tend to dehydrate easily.

    And the good part is I’m not hungry except when I should be, and don’t crave carbs. My diet may seem very controlled and limited, but it works. My husband, who’s the chef in the family, is inventive about spices, herbs and zero or low-carb condiments.

    It works for me, and beats taking more insulin until I absolutely have to.

    I think my perspective may be different, since I went undiagnosed for perhaps as much as two years (yes, I changed doctors!) and when I fell and broke my foot in late 2011 it all went South, and my symptoms, obviously pointing to diabetes on my first visit to the new doctor, were severe. I remember, and don’t want to be that sick again: dietary restrictions seem a small price to pay for avoiding a recurrence of polydipsia, polyuria, severe hypos, blurred vision, extreme weight loss, exhaustion, night terrors and terrible dreams…not to mention avoiding the necessity for, say, amputation of an extremity.

    Another positive outcome of my dietary limitations is that I simply don’t focus on food any more, an extension of years of work as a Weight Watcher. I may sometimes regret the loss of those beans or that juicy apple, but I know how they’d make me feel, and what their effects in high blood sugars would do to me.

    So: bring ON those veggie recipes…but kep the carb count LOW! 🙂

  • Barbara Edwards

    I, too, like Dr. Bernstien’s book, The Diabetic Solution, which recommends no more than 24 gr. carbs in a 24 hour period. If I eat more than about 50 gr. of carbs at a meal (while maintaining goog BG control), I feel bloated and very sluggish.

    I was diagnosed by accident at a health fair when I was 38. Several years later a doctor said I was IDDM (insulin dependent diabetes mellitus). I think I’m LADA.

    About 15 years ago I saw an endocrinologist who said that some people are very sensitive to carbs, and he recommended that I cut out most of the carbs I was consuming. Since I did that, my A1C has been averaging 5.9%. I’m 5’3″ and weigh 115. I take regular insulin 3x/day and use Humalog to fine tune things as needed (which isn’t very often). Since I took steps to control my carb intake, I’ve been feeling great.

  • Geri B

    I have been a diabetic since 2006 and the best low carb diet I have followed and got off insulin is the Dukan diet. Which consist of one day all protein. and the 2nd day protein and veggies. keep this up till you loose the given amount of weight you want to loose. Then next you slowly introduce back breads grains and fruits. go to Dukandiet.com and check it out.