What you need to know about sugar and insulin resistance
- How can you tell if you have insulin resistance (damaged carbohydrate metabolism)? What are some of the common clues? What tests can you ask your doctor to run?
- How much sugar is safe for you to eat? How much fructose and glucose is in your favorite foods, drinks, and sweeteners?
- What can you do to take control of your health? I’ve included an infographic of 10 simple strategies that go beyond cutting added sugars, to improve your metabolism and prevent/treat common diseases.
[Note: this article is part three of a five-part series on sugar and health. To begin with article one, see "Has Fructose Been Framed?"]
Earlier in this series we discovered that fructose is not scarier than glucose. In fact, consuming too much glucose is even riskier than consuming too much fructose because glucose is a more powerful trigger for insulin resistance. It is excess glucose that raises blood sugar and insulin levels, turns off fat burning, shifts fat and cholesterol production into overdrive, feeds cancer cells, and sets the stage for inflammation throughout the body. People with insulin resistance are at high risk for developing type 2 diabetes in the future, so insulin resistance is often referred to as “pre-diabetes.”
So, should you focus on reducing the amount of glucose-y food you eat and lean towards fructose-y foods instead?
Good luck with that . . . people talk about fructose as though it’s a separate sugar from glucose, but practically speaking, it’s not. In real foods, fructose never exists alone—wherever fructose is, glucose is right there beside it, so it’s not easy to separate them in your diet. Even the vast majority of manufactured foods and beverages contain a mixture of fructose and glucose, as you’ll see in the infographic later in this post.
Luckily, it doesn’t matter. All sugars and starches ultimately break down into glucose and/or fructose in your body, and your body turns a lot of the fructose you eat into glucose anyway (see article one). This means that overeating ANY kind of sugar jeopardizes your good health. Too much sugar of any kind can cause insulin resistance, sending you on a path to chronic diseases, including: obesity, cancer, heart disease, erectile dysfunction, fatty liver disease, polycystic ovarian syndrome (PCOS), type 2 diabetes, gout, and Alzheimer’s disease.
Who wants any of those? Nobody.
That is why, no matter what type of diet you eat, how healthy you are right now, or how much you weigh, it is extremely important to take control of your sugar intake.
How much sugar is too much?
It depends on who you are, and what kind of sugar we’re talking about.
Eating sugar is a game of Russian roulette—risk varies from person to person. There’s no way to know for sure what the safe threshold is or which diseases you will get if you overdo it. However, we do know that some people can get away with more sugar than others.
There are two types of people in the world: insulin sensitive and insulin resistant. These exist on a spectrum.
There are two types of carbohydrates in the world: naturally-occurring sugars and starches and refined carbohydrates. These also exist on a spectrum.
Insulin sensitive people
These people have what is commonly referred to as “good metabolism.” Most can usually get away with eating to their satisfaction without gaining weight or losing control over appetite. Generally speaking, if you are physically and mentally healthy, you feel good, and your body weight is naturally normal and stable, you probably fall into this category. If so, you can probably eat naturally-occurring carbohydrates such as fruits and starchy vegetables relatively safely, just like our healthy ancestors did, without worrying about how many carbohydrate grams you eat per day.
However, you could still easily become insulin resistant if you eat refined carbohydrates, especially as you get older. Carbohydrate metabolism tends to worsen with age. To protect yourself from insulin-resistant conditions down the road, stick to whole foods and hopefully you won’t lose your ability to process carbohydrates later on.
Insulin resistant people
We are the unlucky, growing majority—most of us gain weight easily. If you have insulin resistance, then your carbohydrate metabolism is badly damaged. I’ll show you lots of ways to figure out whether you have insulin resistance shortly. For those of us who are insulin-resistant, the sad truth is that we would be wise to limit ALL types of carbohydrate, including fruits, starchy vegetables, grains and beans, not just added sugar and refined carbohydrates. The happy truth is that since carbohydrates lie at the root of most of our problems, we have the power to change the course of our future simply by changing our diet.
Naturally-occurring sugars and starches
Fruits: All fruits contain sugar (a mixture of fructose and glucose), so they can raise blood sugar and contribute to problems in insulin-resistant people. However, fruits also contain water and fiber, making them more filling than other sweet treats. They also contain fructose and sugar alcohols, which can result in a laxative effect or other uncomfortable symptoms if you overeat them. These ingredients are nature’s built-in stop signs. It is much harder to overdose on sugar by eating whole fruit than it is to overdose on sugar by eating candy, cookies, cake, or by guzzling fruit juice or soda. The sweeter a fruit is, the more dramatically it can raise your blood sugar. Examples of low-sugar fruits are strawberries, blackberries, raspberries, apricots, and papayas. Examples of high-sugar fruits are grapes, pineapples, watermelons, mangoes, and figs.
Vegetables: Most above-ground vegetables that don’t taste sweet (such as lettuce, broccoli, and spinach) are very low in sugar and are safe for everyone’s metabolism. However, any vegetable that tastes sweet contains some sugar (think beets, carrots, acorn/butternut squash), and most root vegetables (potatoes, yams, turnips, etc) are full of starch, which breaks down quickly into pure glucose and can spike blood sugar. Insulin-resistant people would be wise to minimize sweet and starchy vegetables.
Grains and Legumes: Grains (wheat, corn, rice, oats, etc) and legumes (beans, peas, soy, lentils, etc) are very high in starch, most of which breaks down into glucose in our bodies. If you eat these foods whole, their outer bran coating slows down their digestion, so they raise blood sugar more slowly than if you eat them in their more refined forms (ground up into flours or powders). If you have insulin resistance, you should stay away from all legumes and grains, even whole grains.
These include all processed and pure sugars, whether they come from a natural source or not: white sugar, high-fructose corn syrup, glucose syrup, agave syrup, molasses, honey, maple syrup, brown rice syrup, fruit juice concentrates, etc.
Contrary to popular belief:
- Honey is not healthier than other forms of sugar. In fact, it contains more grams of sugar per teaspoon than any other sweetener (see infographic below).
- “High-fructose” corn syrup is not worse than other forms of sugar. White sugar contains 50% fructose and high-fructose corn syrup contains 55% fructose. Numerous studies have confirmed that there is no difference between white sugar (sucrose) and HFCS -55 when it comes to your health.
- Agave syrup is not a natural sweetener. It is manufactured by adding enzymes to inulin, the indigestible starch found in agave roots. Agave syrups contain in the neighborhood of 70% to 90% fructose, making agave syrup the mother of all high-fructose syrups.
Flours and purified/processed starches such as corn starch are also considered refined carbohydrates because they don’t exist in nature and can cause sharp blood sugar spikes. Because flours and refined starches break down rapidly into glucose, most cereals and baked goods are high in sugar, even if they have no sugar added or don’t taste sweet. Examples include bread, pasta, crackers, white rice, and non-sugary cereals like Special K®, Corn Flakes®, and Rice Krispies®.
How much refined carbohydrate can you eat?
Everyone should avoid refined carbohydrates. There is broad agreement in the scientific community that refined carbohydrates are unhealthy for all of us, whether we are insulin-resistant or not, so the less you eat of these the better. Most public health authorities explicitly recommend keeping intake to a minimum.
The World Health Organization (WHO) officially recommends in its new 2015 guideline that people of all ages should limit added sugar to less than 5% of total daily calories. So, if you eat 2,000 calories per day, the WHO says that no more than 100 calories should come from added sugars, including “sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates.” That amounts to 26 grams of sugar per day, which is just over 2 tablespoons of sugar per day, maximum. Keep in mind that the WHO guidelines were created with healthy people in mind, not people with insulin resistance.
So . . . how do you know if you are insulin resistant?
Are you on the road to diabetes? For starters, you can take my quick carbohydrate sensitivity quiz to see if you have common signs and symptoms of insulin resistance.
If you have any of the following health problems, you are likely to have insulin resistance:
- Central obesity (too much belly fat, shaped like an apple instead of a pear)*
- Fatty liver disease
- High blood pressure
- Heart disease
- Polycystic ovarian syndrome (PCOS)
- Erectile Dysfunction
- Alzheimer’s disease (read my article on Psychology Today about how insulin resistance causes Alzheimer’s: "Preventing Alzheimer’s Disease Is Easier Than You Think)"
*While being overweight or having an “apple shape” increase the chances that you have insulin resistance, there are some normal weight “pears” (and even a few underweight folks) who have insulin resistance, so don’t go by weight and shape alone.
Medical tests for insulin resistance
There is no simple direct test for insulin resistance on the market, so most health care providers use a combination of tests along with other information about you to determine how insulin resistant you are. Some of the most useful tests are listed below:
- Fasting insulin
- Fasting blood glucose
- Fasting triglycerides (fat in the blood)
- HDL (so-called “good cholesterol”)
- HsCRP aka highly-sensitive C-reactive protein (a marker of inflammation)
- Uric Acid. For more about insulin resistance and uric acid levels, read "Is Fructose Bad for You?" For more about insulin resistance, uric acid and mental health, read ***
I’ve put together a downloadable PDF of these insulin resistance tests with their target ranges (which vary among clinicians, scientists, and laboratories) to you can see how your numbers compare to healthy values. You may want to take the PDF to your next medical appointment and discuss it with your health care provider. Also included is a new quick and dirty formula you can use to estimate your own insulin resistance by plugging in your fasting blood glucose and triglyceride results.
What to do if you have insulin resistance
If your current numbers don’t look good, or if you already have an insulin-resistant condition such as diabetes or non-alcoholic fatty liver disease, it is extremely important to take action as soon as possible, or your health will continue to decline. But take heart: your fate is NOT sealed! You have SO much more control over your health than you may realize. Want to reverse insulin resistance and all the diseases that come with it? Resist those carbs! Here’s a wonderful TED talk by obesity specialist Sarah Hallberg M.D. about how to treat insulin resistance and Type 2 diabetes with low-carbohydrate diets.
While the cutoff values vary from person to person, most enlightened experts recommend that people with insulin resistance lower their total NET carbohydrate intake to 50 grams per day or less in order to improve metabolism [net carbs = total grams of carbohydrate minus total grams of fiber]. Everyone has a different threshold, so you’ll have to see for yourself. In most cases, carbohydrate cravings will go away within a number of days once you get your carbohydrate intake down low enough. It’s important to avoid refined and high glycemic index carbohydrates, and not to eat all of your daily carbohydrate in one sitting, so aim for no more than 15-20 grams of net carbohydrate from whole foods per meal. It’s perfectly safe to eat no carbohydrate at all, so you don’t have to worry about going too low, only about going too high for your particular metabolism. You’ll know if you’re over your personal limit if your lab tests or health problems are not improving (or are getting worse), you have carbohydrate cravings, or you are gaining weight. In just a few short weeks it is possible to see improvements in appetite control, weight, mental clarity, energy, and even most blood tests!
How to find your sweet spot
How to begin depends on your personality. If you’re an all-or-nothing person who prefers cold-turkey approaches, start by removing almost all carbohydrates for a couple of weeks by eating only meat/seafood/poultry/eggs, healthy fats (olive/palm fruit/avocado/coconut/saturated animal fats), and non-starchy, non-sweet vegetables. Then, if you wish, you can gradually add back healthy whole food sources of carbohydrates until you find your personal limit. If you’re a one-step-at-a-time person, start with your usual diet and gradually remove carbohydrate until you find your personal limit. If you go this route, remove the refined and high glycemic index carbs first, as these are the most powerful triggers for insulin resistance.
One helpful way to track your progress is to invest in a blood glucose monitor so you can check your own blood sugar at home. There are many glucometers on the market, and they vary widely in price and accuracy. I use the Keto-Mojo ketone and glucose meter. It's reliable, accurate, and the strips are affordable. [Because I like their meter, I've partnered with them to offer my readers 15% off of the purchase of a new meter. Just click the link here; no coupon code necessary.]
Many doctors still advise people with insulin resistance, even people with full-blown type 2 diabetes, to continue to eat large amounts of carbohydrate per day. Often these physicians will prescribe blood sugar lowering medicines or even insulin to control your blood sugar, instead of advising you to remove sugar from your diet. They may tell you that your problem is due to too much fat in your diet, or not enough exercise. This advice is outdated, illogical, and misguided. Where does high blood sugar come from in the first place? Foods that contain carbohydrate. If you are confused about whether to follow your doctor’s advice or the advice you’re reading here on this site or on the many other excellent sites that recommend a low-carbohydrate approach to diseases like diabetes, don’t take anyone else’s word for it—do your own experiments and see what works best for you. I am confident you will discover for yourself that carbohydrate restriction is a lot more effective in helping you reach your goals than other approaches.
If lowering your carbohydrate alone is not enough to see results, there are additional tips in the infographic below.
Preventing and fighting insulin resistance
Whether you have insulin resistance or not, if you care about your health, want to cut your medical bills, avoid or get off medications, stay out of the hospital, and greatly increase your chances of living a long, disease-free life, the single most important thing you can do for yourself is to eat as little sugar as you possibly can.
The infographic below includes simple steps you can take to remove hidden sources of sugar in your diet before it does any more damage to your health, along with additional strategies to control your blood sugar and insulin levels. I hope you find it useful, and if you do, please pass it along to others.
Share this infographic on your own site using this embed code:
Still hungry for more information about carbohydrates?
If you are interested in trying a low-carbohydrate or ketogenic diet, my "Ketogenic Diets 101" is a good place to start to learn the basics.
For wonderful information and inspiration, I highly recommend Dr. Andreas Eenfeldt’s website about LCHF (low-carb, high-fat) diets: www.dietdoctor.com
What’s your experience?
Do you have any tips or tricks to share with others about how to cut down on sugar? What have you personally found useful in improving insulin resistance and the diseases associated with it? I would love to hear from you in the comments section below.