Sugar has a bittersweet reputation when it comes to health. Sugar occurs naturally in all foods that contain carbohydrates, such as fruits and vegetables, grains, and dairy. Consuming whole foods that contain natural sugar is okay. Plant foods also have high amounts of fiber, essential minerals, and antioxidants, and dairy foods contain protein and calcium.

Since your body digests these foods slowly, the sugar in them offers a steady supply of energy to your cells. A high intake of fruits, vegetables, and whole grains also has been shown to reduce the risk of chronic diseases, such as diabetes, heart disease, and some cancers. However, problems occur when you consume too much added sugar — that is, sugar that food manufacturers add to products to increase flavor or extend shelf life.

In the American diet, the top sources are soft drinks, fruit drinks, flavored yogurts, cereals, cookies, cakes, candy, and most processed foods. But added sugar is also present in items that you may not think of as sweetened, like soups, bread, cured meats, and ketchup. The result: we consume way too much added sugar. Adult men take in an average of 24 teaspoons of added sugar per day, according to the National Cancer Institute. That’s equal to 384 calories.

If 24 teaspoons of added sugar per day is too much, then what is the right amount? It’s hard to say, since sugar is not a required nutrient in your diet. The Institute of Medicine, which sets Recommended Dietary Allowances, or RDAs, has not issued a formal number for sugar.

However, the American Heart Association suggests that women consume no more than 100 calories (about 6 teaspoons or 24 grams) and men no more than 150 calories (about 9 teaspoons or 36 grams) of added sugar per day. That is close to the amount in a 12-ounce can of soda.

What happens to your body when you eat too much sugar?

The body uses glucose for energy. Glucose is mainly derived from carbohydrates and sugar. When you consume sugar or carbohydrates, the pancreas releases insulin to help the body effectively use the glucose for energy. When you eat, food breaks down into glucose and then insulin takes the glucose to the cells, where it is used for energy, But when you consistently overeat sugar and carbohydrates, that’s when problems can occur.

At this point, the insulin is ‘overwhelmed’ and cannot do its job effectively. This is called insulin resistance. When you have insulin resistance, the cells are starved of energy, so they will send a signal to the body that you need to eat, which leads to hunger and cravings. It can also lead to irritability, poor sleep and excess belly fat.

Having insulin resistance increases the risk of chronic diseases like prediabetes, type 2 diabetes, obesity, heart disease and polycystic ovary syndrome (PCOS), to name a few. To avoid these health issues, it’s important to consume sugar and carbohydrates in moderation and stick to whole-food, unprocessed sources when possible.

Sugar is an ever-present part of our modern diet, but its effects on our health are far from sweet. To be clear, there is nothing inherently wrong with sugar. In fact, the human body uses glucose, a simple type of sugar, as one of its primary sources of fuel.  However, when sugar is eaten in excess, it can have negative effects on the body, including:

• Weight gain and obesity
• Increased risk of chronic health conditions
• Sudden spikes in blood glucose levels
• Higher risk of developing type 2 diabetes
• Tooth decay and dental problems
• Fluctuations in energy levels
• Disrupted sleep patterns
• Mood swings and irritability

Common signs of too much sugar in your body

There are at least 61 different names for sugar on food labels, which can make it difficult to know how much added sugar you’re consuming. So, despite your best efforts to make healthy food choices, you could still be consuming more sugar than you realize.

That can have various health consequences. If you’re not getting enough fruits and vegetables in your diet and not eating balanced meals made up of lean protein, healthy fat, and unrefined carbohydrates, it’s possible that added sugars may be displacing other good-for-you foods. Not only are you likely missing out on vitamins, minerals, and fiber, but all that added sugar could manifest itself in other surprising ways.

Increased hunger and weight gain

If you’re consuming a lot of extra calories through added sugars, increased hunger is one of the first signs. Sugar is satisfying to the taste buds, but it doesn’t really satisfy or fill our stomachs. Without protein, fiber, and healthy fats, which most processed snacks and sugary treats lack, the body burns through sugar quickly and ramps up hunger, which can lead to mindless and even compulsive snacking.

The gut microbiome, an ecosystem made up of more than 100 trillion microorganisms, plays a key role in the body’s self-defense system, according to research. A healthy gut helps our metabolism regulate blood glucose (blood sugar) and insulin levels and, in part, enables our bodies to use lipids and manage cholesterol. When you have added sugar, it damages that ecosystem.

Good bacteria decrease and bad bacteria overgrow, leading to dysbiosis (an imbalance between these bacteria) as well as problems with metabolism and the ability to properly process lipids and cholesterol. What’s more, sugar may damage our fat hormones, including leptin, which inhibits hunger. High sugar disrupts metabolism, in part by interfering with leptin. Eating sugar makes you want to eat more sugar, which makes you more hungry.

Irritability

If you’re feeling moody, irritable, or on edge, stress may not be the only reason — it could be a sign that you’re eating too much sugar. One study suggested that consuming too much added sugar can promote inflammation, worsen mood, and lead to symptoms of depression.

A high-sugar meal or snack without protein and fat quickly spikes your blood sugar, but as your body rushes to process all of it, your energy levels crash, making you feel sluggish and irritable. Also, when there’s low glucose in the bloodstream because your insulin levels have spiked after eating a lot of added sugar, levels of blood glucose in the brain decrease as well. Our brains are absolutely critically dependent on having a normal level of blood sugar to fuel them.

The important thing is to pay attention when you’re feeling off. For example, if you start to feel irritable an hour after you eat a snack or at the same time every day, excess sugar could be to blame. If you notice that’s happening to you a lot, it’s a good opportunity to take a look at what you’re eating.

Fatigue and low energy

Sugar is easily absorbed and digested, so if you’re feeling fatigued, it could be due to the amount of sugar you’re getting in your diet. Sugar is a very quick energy source, so regardless of how much you eat, in 30 minutes you’re going to be hungry again, low on energy, or looking for energy again. Large swings of blood sugar and insulin can also cause energy levels to plummet and affect your overall energy level.

Foods don’t taste sweet enough

If you’ve noticed that foods don’t taste as sweet as they used to, or if you need to add sugar to foods to make them taste good (think: dusting your cereal with brown sugar), it could be that you’re getting too much sugar to begin with. If you’re trying to make healthier choices, say by switching from flavored yogurt to plain yogurt, the difference will be more noticeable.

You train your brain to expect a very high level of sweetness, and when you’re used to that, it can be harder to feel satisfied with foods that are less sweet because you’re primed to expect the high sweet levels. If you’re replacing sugar with artificial sweeteners in your diet, you may also want to give it a second thought. A lot of these sugar substitutes are so much sweeter than actual sugar so it tricks our brains into expecting this insanely high level of sweetness. This can increase sugar cravings overall.

Cravings for sweets

If you’re craving sweets, you may be addicted to the feel-good effects that sugar has on your brain. Sugar targets the brain’s pleasure center (called the mesocorticolimbic pathway), triggering a rise in the so-called “happy hormone” dopamine. This pathway in the brain plays a significant role in the food choices we make, including affecting cravings for sugar.

Put simply, eating sugar increases dopamine, and the dopamine rise itself can increase cravings for sugar, leading to a vicious cycle, according to research.

How Too Much Sugar Affects Your Health?

Some of the most commonly consumed added sugars include cane sugar, high-fructose corn syrup, and honey. According to the 2020-2025 Dietary Guidelines for Americans, added sugars contribute nearly 270 calories to the average American’s daily calorie intake.1

The top sources of added sugar in America are sugar-sweetened beverages, desserts, snack foods, and sweetened coffee beverages. Though added sugar is safe in small amounts, consuming too much added sugar can lead to a number of health issues.

Increasing the risk of heart disease

Heart disease, including coronary artery disease—the most common type of heart disease in the U.S.—is the leading cause of death worldwide. Though a number of factors can impact a person’s risk of heart disease, a diet high in added sugar can contribute to developing heart disease Research shows that diets high in added sugar increase heart disease risk factors such as high triglycerides, elevated blood sugar and blood pressure, obesity, and atherosclerosis—the narrowing of arteries caused by fatty deposits accumulating along artery walls.

A 2022 review that included data on over 100,000 women found that those who consumed 15% or more of their total daily energy intake as added sugar were 20% more likely to develop coronary heart disease compared to women who consumed less sugar. The study also found that consuming one or more servings of sugar-sweetened beverages per day was associated with a modestly increased risk of total heart disease, coronary heart disease, and total risk of stroke.

May cause fatty liver

Consuming too much added sugar, especially in the form of fructose, can damage the liver and cause fat to build up in this critical organ. Fructose is a type of sugar that’s almost exclusively broken down by the liver, where it’s converted into energy to be used by the body or stored as glycogen for later use. However, when too much fructose is consumed from sugary foods and drinks like soda, it overwhelms the liver and causes excess glycogen to be turned into fat. This leads to a buildup of excess fat in the liver, which is known as Non-Alcoholic Fatty Liver Disease (NAFLD).

A 2015 study that included data on 5,908 adults found that people who consumed sugar-sweetened beverages daily had a 56% greater risk of developing fatty liver disease compared to non-consumers.

Increasing the risk of diabetes

Sugary foods and drinks can contribute to diabetes development in several ways. Consuming too much added sugar can lead to a calorie surplus. Consuming too many calories leads to weight gain over time, which can eventually lead to obesity—a key risk factor for type 2 diabetes

Additionally, consuming large amounts of added sugar can lead to elevated blood sugar and resistance to insulin, a hormone that shuttles blood sugar into cells where it can be used for energy. Insulin resistance is when cells stop responding appropriately to insulin, which causes high blood sugar and insulin levels.

A 2021 review of 16 studies found that each serving per day increment of sugar-sweetened beverage intake increased the risk of developing type 2 diabetes by 27%.5 Some evidence suggests that when added sugar is restricted to less than 5% of total calories, it may reduce the risk of developing type 2 diabetes by 50%.

May harm brain health

High-sugar diets have been linked to impaired memory, cognitive decline, and a greater risk of mental health conditions like depression. Studies show that diets high in added sugar can reduce brain volume, which is associated with cognitive decline.

A 2017 study that included 4,276 people over the age of thirty found that those who consumed more than one sugary drink per day had lower total brain volume and poorer memory compared to people who consumed less than one sugary drink per day.

High-sugar diets have also been associated with the development of mental health conditions such as anxiety and depression. A 2017 study that included data on 23,245 people found that men who consumed the most added sugar had a 23% increased risk of developing common mental disorders (CMD), which includes depressive and anxiety disorders, after 5 years.