8 ways eating too much sugar is bad for your health

From diabetes to tooth decay, these health risks may make you want to swap your candy bar for kale.

Amanda Capritto
6 min read

Sugar, in all its forms, can be a detriment to your health if you don't watch your consumption. 

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Sugar: The oh-so-sweet ingredient that seems to have a place in anything you can buy off of store shelves. Nutrition guidelines change as researchers discover new findings and develop new theories, but over decades of scientific research, one thing remains the same: Eating too much sugar is bad for your health. 

Sugar by itself is not a bad guy, Dr. Murali Doraiswamy, professor of psychiatry and medicine at Duke University School of Medicine, tells CNET. "Sugar is vital to the human body," he says, noting important functions that sugar fulfills, such as providing your brain with energy and serving as the backbone of your DNA.

Problems arise when you consume more sugar than your body needs, Doraiswamy says, and such problems are many: From diabetes to tooth decay, learn how too much sugar befouls your body. 

Read more: How sugar can temporarily sabotage your immune system

1. Sugar can make it hard to manage your weight


If you're having trouble losing or managing your weight, take a look at how much sugar you consume on average. 

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For people who have a hard time losing weight or maintaining a healthy weight, sugar adds fuel to the fire: It's more than clear that excessive sugar consumption is linked to weight gain and obesity

Studies show that consuming certain types of sugar (namely fructose, which is in most processed foods and sugary drinks), can increase your hunger and influence cravings. Other research shows that too much sugar can interfere with important hunger and appetite signaling hormones and increase visceral fat, the harmful type of body fat that lies deep in your abdomen.

Doraiswamy does note that recent data over the past decade shows that sugar consumption is declining. But obesity rates are still rising, which suggests that there's more to obesity than just sugar consumption.

2. It can lead to nutrient deficiencies


A healthy diet consists of a wide variety of protein, grains, fruits and vegetables. Eating too much sugar might prevent you from getting the range of foods you need. 

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The type of sugars that people eat too much of are "free sugars," Doraiswamy says, or sugars added to processed foods -- you probably know them as "added sugars." If too much of your diet comes from processed foods with added sugars, you may preclude yourself from eating other foods with vital nutrients. 

For example, Doraiswamy says, "I had a patient who was addicted to eating several Snickers bars on-the-go everyday." If you're eating several candy bars in a day, you can become full on those sugar-laden calories and deprive yourself of a balanced diet. There's a slim chance that you have much room for nutritious snacks and meals when the majority of your diet consists of added sugars. 

The 2015-2020 Dietary Guidelines for Americans recommend that no more than 10% of your daily calorie intake comes from added sugars. On a typical 2,000-calorie diet, that means no more than 200 calories per day should come from sugar. 

There are four calories in one gram of sugar, so 50 grams of added sugar is the recommended maximum if you eat 2,000 calories per day.

3. Messes with blood sugar control and increases diabetes risk


Sugar can lead to high blood sugar and contributes to the development of diabetes. 

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Just like the link between sugar and obesity is clear, so too is the link between sugar and diabetes. 

A primer on diabetes: Type 2 diabetes develops when your body doesn't respond to insulin or your pancreas doesn't produce enough insulin. Insulin is the hormone that removes sugar from your blood and transfers it to body cells. The result is chronically elevated blood sugar (if diabetes is left untreated), which can lead to other complications, including nerve damage and cardiovascular disease.

Studies show that drinking sugar-sweetened beverages, including fruit juice, increases your risk of type 2 diabetes, although it's important to note that sugar consumption is not the only factor that affects your diabetes risk. Physical inactivity, smoking and alcohol consumption are also known to contribute.

Researchers believe that sugar can both directly and indirectly influence your risk for type 2 diabetes: For example, indirectly by causing weight gain, which is a major risk factor for diabetes; and directly by affecting the way your body processes sugar

4. Can lead to poor dental health


When bacteria in your mouth feed on sugar, cavities can form. 

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Sugar is the main driver of cavities, or tooth decay. Cavities occur when bacteria in plaque feed on sugar left on your teeth. The fermentation of sugar releases acids, which eat into your tooth enamel. Dental plaque is sticky, which keeps the bacteria and acids in close contact with your teeth and, over time, holes in your enamel can develop. 

Excess sugar consumption -- especially if combined with poor oral hygiene -- can lead to tooth decay and the need for cavity fillings or other dental procedures. Artificial sugars, while not the solution for all health needs, can help if you are prone to dental cavities. 

5. Can increase risk of depression


Sugar consumption has been linked to increased depressive symptoms.

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You probably know anecdotally how your diet affects your mood -- that some foods give you long-lasting energy and make you feel good, while others result in a crash and send your mood plummeting. 

Those anecdotes aren't incidental: Evidence implies that your diet really can affect your mood, so much so that it can actually influence your risk for mood disorders. In fact, there's an entire arm of mental health research dedicated to this concept called nutritional psychiatry

"Progressively higher consumption of dietary added sugars was also associated with increasing odds of incident depression," concludes one study on more than 69,000 women. Another indicates that drinking sweetened beverages can increase the risk of depression among older adults and yet another suggests that eating a diet rich in whole, nutritious foods can have a protective effect against depression.

6. Sugar is associated with cardiovascular diseases

A red heart-shaped stethoscope on a teal background.

While fat usually gets pointed at as the cause of heart disease, sugar too can contribute.

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Heart disease and stroke are two of the most serious complications associated with excessive sugar consumption, Doraiswamy says. Scientific evidence links high-sugar diets to cardiovascular disease risk factors, including obesity, inflammation, high triglycerides and high blood pressure.

Other research states that there is a "significant relationship between added sugar consumption and increased risk for [cardiovascular disease] CVD mortality." One groundbreaking study in 2016 found that sugar consumption was more closely related to heart disease than saturated fat, which challenged the traditional train of thought that a high-fat diet is the number one cause of heart disease.

7. May accelerate cognitive decline


Pass up the sugar for a healthy brain. 

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Another often-overlooked complication of sugar consumption is cognitive decline, Doraiswamy says. "People with high blood sugars tend to have faster rates of cognitive decline," he says, something that scientists are starting to refer to as "diabetes of the brain."

Sure enough, research suggests that consuming too much sugar, specifically sugar-sweetened drinks, may increase the risk of dementia. Research also indicates that changes in the brain may start years before any clinical symptoms of cognitive decline appear -- a 2020 study shows that dietary interventions in early adult life can help protect your brain as you age.

8. It has been linked to skin issues


The evidence linking diet (specifically sugar) and acne is limited, but scientists agree there is some connection.

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Growing up, you were probably told to stop eating chocolate if you wanted your acne to clear up. While there's no proof that chocolate alone leads to acne, eating too much sugar from any source can increase your risk of developing skin issues, including acne: Research shows that eating a high-glycemic diet can play a role in acne development

Population studies have suggested that acne is more prevalent in Western societies, such as the US, where diets high in fat, sugar and processed foods are common. While still a controversial topic -- further studies are needed to confirm the relationship between diet, sugar and acne -- scientists say the link between diet and acne "can no longer be overlooked." 

How to eat less sugar


Eating less sugar doesn't have to mean boring plates. 

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The easiest way to cut sugar from your diet is to eat fewer processed foods. It's hard to find processed foods without any added sugar -- even healthier items may be packed with sugar, often disguised as something like agave nectar or coconut sugar. 

To make sure you eat a balanced diet rich in all of the essential vitamins and nutrients, you should follow the Dietary Guidelines for Americans, which outline the recommended daily intake for almost every nutrient currently known to man. 

And, again, not all sugar is bad: Sugar from fruits and vegetables is accompanied by fiber, minerals and vitamins. Even added sugar isn't bad all the time -- no one says you can't enjoy a piece of cake at a birthday party. 

Healthful sugar consumption is all about watching your overall intake day-to-day, curbing your consumption when it's too high and exercising regularly to offset the effects of sugar, especially if you sit for most of the day.

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The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.