Medically Reviewed by Michael Dansinger, MD on June 06, 2020

The Bitter Side of Sugar


Sugar is sweet, but too much of it can sour your health. Whole foods like fruits, veggies, dairy, and grains have natural sugars. Your body digests those carbs slowly so your cells get a steady supply of energy. Added sugars, on the other hand, come in packaged foods and drinks. Your body does not need any added sugars.

How Much Is Too Much?


The American Heart Association recommends no more than 6 teaspoons (25 grams) of added sugar a day for women and 9 teaspoons (36 grams) for men. But the average American gets way more: 22 teaspoons a day (88 grams). It’s easy to overdo. Just one 12-ounce can of regular soda has 10 teaspoons of sugar -- and no nutritional benefit.

Harm: Weight Gain


Sugar-sweetened beverages are a big source of added sugars for Americans. If you drink a can of soda every day and don’t trim calories elsewhere, in three years you’d be 15 pounds heavier. Putting on too much weight can lead to problems like diabetes and some cancers.

Harm: Heart Disease


One in 10 Americans gets 1/4 or more of their daily calories from added sugar. If you eat that much, one study found that you’re more than twice as likely to die from heart disease than someone who gets less than half as much. It’s not clear why. It could be that the extra sugar raises your blood pressure or releases more fats into the bloodstream. Both can lead to heart attack, stroke, and other heart diseases.

Harm: Diabetes


Sugary drinks in particular can boost your odds for type 2 diabetes. That can happen because when sugar stays in your blood, your body may react by making less of the hormone insulin, which converts the food you eat into energy. Or the insulin doesn’t work as well. If you’re overweight, dropping even 10-15 pounds can help you manage your blood sugar.

Harm: High Blood Pressure


Usually, salt gets the blame for this condition, also called hypertension. But some researchers say another white crystal -- sugar -- may be a more worrisome culprit. One way they believe sugar raises blood pressure is by making your insulin levels spike too high. That can make your blood vessels less flexible and cause your kidneys to hold onto water and sodium.

Harm: High Cholesterol


Sugary diets are bad for your heart, regardless of how much you weigh. They can:

  • Raise your so-called "bad" (LDL) cholesterol and lower the "good" (HDL) kind.
  • Hike blood fats called triglycerides and hinder the work of an enzyme that breaks them down.

Harm: Liver Disease


Most packaged foods, snacks, and drinks are sweetened with fructose, a simple sugar from fruits or veggies like corn. Your liver turns it into fat. If you regularly pump fructose into your body, tiny drops of fat build up in your liver. This is called non-alcoholic fatty liver disease. Early diet changes can reverse it. But over time, swelling and scarring can damage your liver.

Harm: Cavities


You know sugar rots your teeth. How? It feeds the bacteria in your mouth, which leave behind acid that wears away your tooth enamel. Sugary drinks, dried fruits, candy, and chocolate are common offenders. Sour candies are among the worst. They’re almost as acidic as battery acid! If you eat tart treats, rinse your mouth with water afterward or drink some milk to neutralize the acid.

Harm: Poor Sleep


Too much sugar during the day can mess with your blood glucose levels and cause energy spikes and crashes. You may struggle to stay awake at work or doze off in class at school. In the evenings, a bowl of ice cream or cookies can pump you with sugar that can wake you up at night. It also can cut short the time you’re in deep sleep. So you may not wake up feeling refreshed.  

Possible Harm: ADHD


It’s a common perception that sugar worsens the symptoms of attention deficit hyperactivity disorder. But the link is unproven. More studies knock down the theory that sugar causes or worsens ADHD than support it. We don’t know exactly what leads to ADHD, but your genes probably play a large role.

Harm: Mood Problems


Feeling down? Your sweet tooth may be part of the problem. Several studies have linked sugar and mental health problems. One of the latest showed that men who ate more than 66 grams of sugar a day -- almost double what’s recommended -- were 23% more likely to be diagnosed with anxiety or depression than men who ate 40 grams or less. Too much sugar could fuel depression through swelling, or inflammation, in your brain, which is more common in people with depression.

Harm: Gout


You may know that you can get this painful arthritis from eating too much red meat, organ meats, and lobster. The same goes for fructose. It can make uric acid build up in your blood, which in turn forms hard crystals in your big toe, knees, and other joints.

Harm: Kidney Stones


You get these when chemicals in your pee turn into solid crystals. Your body flushes out some kidney stones without much pain. Others can get stuck in your kidney or another part of your plumbing and block urine flow. Too much fructose -- from table sugar, high-fructose corn syrup, or processed foods -- raises your chances for kidney stones.

Harm: Aging


Sugary drinks may add years to your biological age. DNA called telomeres cap the end of your chromosomes to protect them from damage. Longer is better. Shortened telomeres may go hand in hand with age-related diseases like diabetes. One study found that people who drink 20 ounces of soda a day have shorter telomeres. Researchers figure that’s like adding more than 4 years to the age of your cells.

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Harvard Medical School: “The sweet danger of sugar,” ‘Eating too much added sugar increases the risk of dying with heart disease,” “Abundance of fructose not good for the liver, heart.”

American Heart Association: “Added Sugars.”

Harvard School of Public Health: “Added Sugar in the Diet,” “Soft Drinks and Disease.”

American Diabetes Association: “Getting Started with Type 2 Diabetes,” “Weight Loss.”

Open Heart: “The wrong white crystals: not salt but sugar as aetiological in hypertension and cardiometabolic disease.”

Cleveland Clinic: “Why a Sweet Tooth Spells Trouble for Your Heart,” How Strong Is the Link Between Inflammation and Depression?

National Health Services (UK): “Which foods cause tooth decay?”

Minnesota Dental Association: “Pucker Up! The Effects of Sour Candy on Oral Health.”

National Sleep Foundation: “Sweet Dreams: How Sugar Impacts Your Sleep.”

National Institutes of Health/Medline Plus: Causes of ADHD

Scientific Reports: “Sugar intake from sweet food and beverages, common mental disorder and depression: Prospective findings from the Whitehall II study.”

University College London: “High sugar intake linked with poorer long-term mental health.”

Arthritis Foundation: “8 Food Ingredients That Can Cause Inflammation,” “Fructose and Gout.”

National Kidney Foundation: “Kidney Stones.”

American Journal of Public Health: “Soda and Cell Aging: Associations Between Sugar-Sweetened Beverage Consumption and Leukocyte Telomere Length in Healthy Adults From the National Health and Nutrition Examination Surveys.”

The American Journal of Clinical Nutrition: “Glycemic index, glycemic load, and blood pressure: a systematic review and meta-analysis of randomized controlled trials.”