11 Signs You Might Have A Sugar Intolerance

Here’s what experts say.

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11 signs of a sugar sensitivity, according to experts.

Not everyone has a problem with sugar. Plenty of people add it to their coffee or have a slice of cake and feel a-OK. But then there are the ones who don't tolerate sugar well and feel sick, and possibly even experience strong cravings, after eating and/or drinking it.

While that may sound a bit dramatic, it is a pretty common reaction. "When you consume sugar, blood sugar levels in the body increase, which leads to the release of insulin from the pancreas," Kimberly Hershenson, LCSW, a New York City-based therapist specializing in eating disorders, tells Bustle. "People get a burst of energy and feel good momentarily, however, blood sugar levels rapidly decrease." This is what's known as a "crash," and it can leave you feeling bad.

Apart from affecting your blood sugar levels, a diet high in sugar can also lead to inflammation, and may even mess with your hormones. Keep in mind, though, that not all sugars are created equal. "Most human beings are 'sensitive' to simple sugars because they hit the bloodstream so quickly," Amanda L. Dale, M.Ed., M.A., a personal trainer and nutritionist, tells Bustle. This is why you might feel weird after eating sugar or crave more of it after eating chocolate or drinking a sugary coffee, but not necessarily after eating a piece of fruit.

If you suspect your current eating habits might be negatively impacting your health, then you might want to consider limiting your sugar intake, or consulting with your doctor on how much sugar is a good amount for you. Read on for some symptoms of sugar sensitivity to watch out for, according to experts.

1. Your Skin Has Been Breaking Out


While there are many contributing factors when it comes to acne, eating many sugary foods is often one of the main culprits.

"Skin is incredibly sensitive to sugar," Laura McGevna, M.D., a board-certified dermatologist in Vermont, tells Bustle. "We know that 'high glycemic index' or foods that increase blood glucose easily are associated with worsening of acne. This is likely due to an insulin response that stimulates a cascade of endocrine and hormonal events that cause inflammation on the skin."

Of course, this doesn't mean you can't have sugar. But if your skin is bothering you, you may want to consider what you're eating. "If you notice that your skin seems more inflamed, you are developing new rashes or breakouts, and you've been burning the candle at both ends [...] this is a strong indication that you need to back off, listen to your body, and put your health first," McGevna says.

2. You Can't Get To Sleep At Night

Again, there are many factors to consider here, like your caffeine intake, stress levels, etc. But a lifestyle high in sugar might also be what's keeping you up at night. As Hershenson says, sugar can prevent the body from getting into deep sleep mode.

Studies have shown a connection between shorter sleep and drinking sugar-sweetened beverages. While new research needs to be done, it won't hurt to limit how much sugar you consume during the day, but especially before bed. Like caffeine, it isn't something you'll want to have in the evening, in particular.

3. You've Been Feeling Emotional Lately


An unstable mood can be caused, in many ways, by blood sugar fluctuations, which Hershenson says can impact how you feel. Studies have also shown a connection between the intake of sweet foods, beverages and added sugars, and symptoms of depression.

What you eat really can play a large role in how you feel overall, including mentally and emotionally. While speaking with a therapist will always be a good idea if you aren't feeling like yourself, it can also help to pay attention to what you're eating on a daily basis.

If you're consuming a lot of sugar, you might notice a big difference if you balance out meals in a way that keeps your blood sugar even. Or by lessening your sugar intake and seeing how that makes you feel.

4. You're Always Exhausted After Eating

Take a moment to think about how you feel after eating a sugary (or carb-heavy) meal. If you need a cup of coffee or start to fall asleep at your desk at work, it could be due to wavering blood sugar levels.

"People who process sugar normally and quickly tend to feel energized, satiated, and calm after ingesting sugar," Dale says. "People who are more sensitive to it feel tired, irritable, and tend to actually crave more sugar, aka the withdrawal/addiction response."

It's this craving that'll send you pawing through your desk, looking for candy or cookies or something to help you get through the rest of the day. And that can be a sign sugar isn't agreeing well with your body.

5. You Get Shaky Or Lightheaded


If you suffer from low blood sugar, you might have a condition called hypoglycemia, which can leave you "feeling tired, hungry, weak, shaky, lightheaded, and anxious," Kelly Leveque, holistic nutritionist and author of Body Love, tells Bustle. "As a result, [you] crave sugar and carbohydrates, thinking they will pick [you] back up. In reality, they start the cycle all over again."

So if you find yourself in the vicious cycle of having a sugar snack, then getting lightheaded, then feeling better after having a sugary snack, let a doctor know.

6. You've Been Struggling With Sinus Issues

Have you been feeling extra stuffy as of late? "In the large majority of people, these symptoms are coming from candida overgrowth," Dr. Jacob, Teitelbaum, author of Beat Sugar Addiction Now!, tells Bustle. A lifestyle high in sugar can cause candida, or yeast, to get a bit out of control in your body, leading to sinusitis, congestion, and other chronic nasal issues.

While the research is limited, one study noted that higher sugar consumption may be associated with increased inflammatory stress and sinonasal symptoms. When in doubt, it won't hurt to do an experiment of your own, and see how you feel when you cut back on sugar.

7. You Seem To Be Bloated All The Time


If you have bowel issues, such as IBS, gas, diarrhea, or constipation, it could also be due to a sugar-induced candida overgrowth. "Yeast grows by fermenting sugar, and when [you eat a lot of sugar] you are firing up a fermentation tank in your gut," Teitelbaum says. "And fermentation makes lots of gas. And so will you, if you drink a lot of sugary drinks."

It's fine if you don't mind the side effects of sugar intake, or want to risk it in order to have the occasional sugary drink. But what you eat can obviously have an impact on how you feel in the abdominal region, including how bloated you become as a result. And it just might not be worth it.

8. You Feel Distracted & Scattered Throughout The Day

You've probably heard of a little thing called brain fog, which is that fuzzy out-of-it feeling that causes you to space out at work or forget where the heck you put your keys. As Sharla Mandere, CHHC, a holistic health and wellness coach, tells Bustle, sugar can cause these issues, and even lead to a lack of focus.

And this is particularly true if you have symptoms of adrenal fatigue, Dr. Carrie Lam, MD, DABFM, who is board certified in family medicine, tells Bustle. "When you eat too much sugar it forces your body to make extra insulin and cortisol," she says, which can wear you down over time.

If you haven't been feeling like yourself — checked out, tired, and lacking motivation — cutting back on sugar may be a big help.

9. You Have Cravings & Are Often "Hangry"


If you constantly crave sugar, or can't seem to feel "full" despite eating plenty of food, it may be that what you are eating has you on a sugar rollercoaster. As Mandere says, cravings — usually for sugar — can be caused by sinking blood sugar levels. "This can be translated into the afternoon pick-me-up of sugary coffee, drinks, or sugary snacks," she says.

Sound familiar? If so, replacing that afternoon sugar hit with something that keeps your blood sugar stable, like protein, can make all the difference.

10. Your Knees Have Been Hurting

Aches and pains — and other general health issues — are often caused by inflammation in the body, which is another negative side effect of consuming a lot of sugar throughout the day. "Regular blood sugar spikes can eventually lead to general inflammation, which can then contribute to premature aging, digestive abnormalities, [and] joint pain," Lauren Minchen MPH, RDN, CDN, a nutritionist, tells Bustle. Basically, if you feel like you're fallin' apart, it may be time to make some changes.

11. You Constantly Run Out Of Motivation


Aside from flagging energy levels, take note if you've been lacking motivation lately. "If you feel drowsy and tired after eating a sugar-heavy snack, then you should realize that your body is not burning or storing glucose at the rate you are consuming it," nutritionist Parker Condit tells Bustle. "In addition to this being a lousy way to live, it's also an indicator that something is wrong [...] If all you feel like doing is sleeping and lounging around, then it's time to start being more aware of what you are consuming."

It may be that eating a lot of sugar isn't working for you, and that it's officially time to consider eating and drinking less of it. It can certainly take some time to get used to the change, and it doesn't mean you can't have sugar on occasion. But sometimes the payoff is worth the initial adjustment phase, especially when it comes to your health.

Studies referenced:

Avena, N. (2009). Evidence for sugar addiction: Behavioral and neurochemical effects of intermittent, excessive sugar intake. Neurosci Biobehav Rev.

Della Corte, K. (2018). Effect of Dietary Sugar Intake on Biomarkers of Subclinical Inflammation: A Systematic Review and Meta-Analysis of Intervention Studies. Nutrients.

St-Onge, Marie-Pierre. (2016). Effects of Diet on Sleep Quality. Advances in Nutrition. 7(5): 938–949. doi: 10.3945/an.116.012336

Katta, R. (2014). Diet and Dermatology. The Journal of Clinical and Aesthetic Dermatology.

Knuppel, Anika. (2017). Sugar intake from sweet food and beverages, common mental disorders and depression: prospective findings from the Whitehall II study. doi: 10.1038/s41598-017-05649-7

Macdonald, I.A. (2016). A review of recent evidence relating to sugars, insulin resistance and diabetes. European Journal of Nutrition.

Park, C. (2020). Glucose metabolism responds to perceived sugar intake more than actual sugar intake. Scientific Reports.

Rawahi, S.H. (2018). Factors related to reducing free sugar intake among white ethnic adults in the UK: a qualitative study. BDJ Open.

Reynolds, R. (2010). Effect of the Glycemic Index of Carbohydrates on Acne vulgaris. Nutrients.

Satokari, R. (2020). High Intake of Sugar and the Balance between Pro- and Anti-Inflammatory Gut Bacteria. Nutrients.

A, Sawani. (2018). Limiting Dietary Sugar Improves Pediatric Sinonasal Symptoms. Journal of Medicinal Food. 21(6):527-534. doi: 10.1089

Thayer, R.E. (1987). Energy, tiredness, and tension effects of a sugar snack versus moderate exercise. J Pers Soc Psychol.


Kimberly Hershenson, LCSW, NYC-therapist specializing in eating disorders

Laura McGevna, MD, board-certified dermatologist

Amanda L. Dale, M.Ed., M.A., personal trainer and nutritionist

Kelly Leveque, holistic nutritionist and author of Body Love

Dr. Jacob Teitelbaum, author of Beat Sugar Addiction Now!

Sharla Mandere CHHC, holistic health and wellness coach

Lauren Minchen MPH, RDN, CDN, nutritionist

Parker Condit, nutritionist

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