Is Sugar Good or Bad for You? Here’s What You Need to Know

Sugar is a simple carbohydrate that provides energy to the body, but its health effects depend on the type and amount consumed. In this comprehensive guide, we explain what sugar is, how it functions in the body, current intake guidelines, and how to balance its benefits and drawbacks. We also explore the benefits of natural sugars, the dangers of excessive consumption, signs you may need to cut back, and safe ways to enjoy sweetness. This information is sourced from reputable organisations, including the World Health Organisation (WHO), the Centres for Disease Control and Prevention (CDC), and the American Heart Association (AHA).

What Is Sugar?

Sugar is the generic name for sweet-tasting, soluble carbohydrates. The most common sugars in our diet are monosaccharides (single sugars) and disaccharides (double sugars). Glucose and fructose are monosaccharides, while sucrose (table sugar) and lactose (milk sugar) are disaccharides composed of two monosaccharides. For example, sucrose is a combination of glucose and fructose. When foods contain these sugars naturally (in fruits or milk), we refer to them as natural sugars. When sugars or syrups are added to foods during processing or preparation, they are referred to as added sugars.

Added or refined sugar—such as granulated sugar (sucrose from cane or beet) and high fructose corn syrup—is often found in sweets, soda, and processed foods. Unlike natural sugars, added sugars contribute calories with little or no nutritional value. For example, the CDC notes that added sugars “contribute calories but no other nutritional value”. In contrast, natural sugars in whole foods come packaged with fibre, vitamins, and minerals. As one university nutrition centre points out, although fruit contains sugar, it also provides vitamins, minerals, fibre, and phytochemicals – plant-produced compounds with health benefits. In fact, fruits offer many health perks, including immune support, cancer prevention, a healthy heart, and more.

Sources of Sugar: Naturally occurring sugars are found in fruits, vegetables, milk, and other whole foods. Added sugars are found in soft drinks, candies, baked goods, sweetened cereals, sauces and condiments. For example, the WHO notes that even unexpected foods, such as ketchup, can contain sugar (approximately 1 teaspoon per tablespoon), and a regular soda can contain up to 40 grams (≈approximately 10 teaspoons) of added sugar. Health authorities emphasise that hidden sugars in processed foods are a significant reason many people exceed the recommended limits.

Key point: Sugars encompass both natural sugars (found in fruits, vegetables, and milk) and added or refined sugars (found in sweets, soda, and other processed foods). Refined sugars are high in calories and low in nutrients, while natural sugars come with fibre and nutrients that benefit health.

How Sugar Affects the Body

When you consume sugar or any other carbohydrate, your digestive system breaks it down into simple sugars, primarily glucose, which enter the bloodstream. This raises your blood sugar level. As blood sugar levels rise, the pancreas releases insulin, a hormone that signals cells to absorb glucose and either use it for energy or store it for later use. As cells take up glucose, blood sugar levels fall. When blood sugar levels drop, the pancreas releases glucagon, prompting the liver to release stored glucose and maintain stable blood sugar levels. This insulin–glucagon interplay ensures that tissues, particularly the brain, have a steady supply of fuel.

Digestion and Blood Sugar

Simple sugars, such as glucose and fructose, are absorbed quickly, causing blood sugar levels to spike more rapidly. Complex carbohydrates and whole foods are digested slower, causing a gentler rise in blood sugar. In other words, eating plain sugar (simple carb) “often lead[s] to a faster rise in blood sugar and insulin secretion”. In contrast, complex carbs (such as whole grains and vegetables) contain fibre and take longer to break down, which means they have less of an immediate impact on blood sugar.

Insulin’s role: When insulin levels rise, muscle and fat cells open up to take in glucose from the blood. If the body’s cells become resistant to insulin (a condition known as insulin resistance), blood sugar and insulin levels remain high even after eating. Over time, insulin resistance can wear out the pancreas and lead to type 2 diabetes. The Harvard Nutrition Source explains that type 2 diabetes “usually develops gradually when muscle and other cells stop responding to insulin,” causing prolonged high blood sugar levels.

Energy use and storage: Glucose is the body’s preferred energy source. Cells use glucose for immediate energy needs, and excess glucose is stored as glycogen in the liver and muscles. Once glycogen stores are full, extra sugar can be converted to fat. The brain, which has high energy demands, relies heavily on glucose – so maintaining balanced blood sugar is crucial for proper brain function. If blood sugar levels are erratic (spiking high and then crashing), people may experience fluctuations in their energy and mood.

Insulin and Carbohydrate Intake

Insulin: As noted, insulin is a key hormone that regulates sugar levels. It helps lower blood sugar by facilitating the movement of glucose into cells. When you consume a lot of sugar, insulin levels rise significantly to clear the glucose from your bloodstream. In healthy individuals, this helps prevent blood sugar levels from becoming too high. However, with long-term high sugar intake, chronic high insulin can promote fat storage and lead to insulin resistance. High insulin levels can also raise triglycerides and blood pressure, linking sugar intake to an increased risk of heart disease.

Blood sugar levels: High blood sugar levels can be harmful. It can damage blood vessels and organs over time. Reducing large sugar spikes (for example, by eating fibre-rich foods and controlling portions) helps prevent this damage. The Harvard Nutrition Source highlights that fibre “slows down digestion, delaying blood sugar rises after meals,” which means choosing whole fruits over fruit juice or candy can help blunt spikes and improve blood sugar control.

Brain and sugar: Glucose is the brain’s primary fuel, but the brain only needs a steady amount. Interestingly, the WHO notes that sugars in fresh fruits, vegetables, and milk are not associated with health problems because the body handles these sources differently. The presence of fibre and nutrients, along with natural sugars, likely explains this difference.

Glycemic Index: Foods differ in how much and how fast they raise blood sugar. High-glycemic foods, such as white bread or soda, are quickly digested and cause sharp spikes in blood sugar levels. In contrast, low-glycemic foods, such as whole oats or non-starchy vegetables, digest slowly, resulting in a gradual rise in blood sugar. Eating too many high-glycemic foods “can lead to an increased risk for type 2 diabetes, heart disease, and overweight”.

Key point: After eating sugar, blood sugar rises, triggering insulin to help cells absorb glucose for energy or storage. Foods high in added or refined sugars cause rapid spikes in blood sugar and insulin, which, over time, can promote weight gain and insulin resistance. Natural sugars in fibre-rich foods raise blood sugar more slowly, supplying steady energy.

Daily Sugar Intake Recommendations

Health organisations worldwide recommend limiting added sugars to promote health and reduce the risk of chronic diseases. The CDC and the Dietary Guidelines for Americans advise that children over the age of 2 and adults consume less than 10% of their daily calories from added sugars. For a typical 2,000-calorie diet, that’s no more than 200 calories (about 50 grams or 12 teaspoons) per day from added sugars. The CDC also highlights that children under 2 should have virtually no added sugars in their diets.

The World Health Organization (WHO) echoes this guidance. In 2015, WHO issued a guideline calling for free sugars (added sugar plus sugars in honey, syrups, and fruit juices) to be less than 10% of total energy intake for adults and children. WHO goes further, suggesting that reducing free sugars to below 5% of calories (approximately 25 grams or 6 teaspoons) would yield additional health benefits. The WHO’s Director of Nutrition states that “keeping intake of free sugars to less than 10%… reduces the risk of overweight, obesity, and tooth decay.” In other words, both WHO and CDC agree: aim for as low added sugar as possible, certainly under 10% of calories, ideally under 5%.

The American Heart Association (AHA) offers even stricter guidelines. AHA recommends that women consume no more than about 6 teaspoons (100 calories) of added sugar per day and men no more than 9 teaspoons (150 calories). This amounts to about 25 grams for women and 37.5 grams for men, which is roughly 6% of a 2,000-calorie diet. The AHA notes that “added sugars contribute zero nutritional benefits” and should be used only after meeting basic nutritional needs, thereby utilising discretionary calories.

These guidelines help translate percentages into everyday terms. WHO says <10% of calories from free sugar, which is <50 grams (12 teaspoons) for a 2,000-calorie diet. They add that less than 5% (≈25 grams or 6 teaspoons) is even better. The AHA’s stricter advice (6 tsp for women, 9 tsp for men) essentially aligns with 100-150 calories or about 6-9% of calories. In practice, one 12-ounce can of regular soda contains approximately 10 teaspoons of sugar, which is roughly the entire daily added sugar allowance for many adults.

Key point: Health authorities uniformly advise keeping added/free sugar low. Aim for less than 10% of calories from added sugar (some say <5% for extra benefit). In practical terms, that’s about 6–12 teaspoons of sugar per day, depending on your calorie needs. Children under 2 should have virtually no added sugar.

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Benefits of Natural Sugars

Not all sugar is created equal. Natural sugars—those found in whole fruits, vegetables, dairy, and grains—come with beneficial nutrients and fibre that improve health. In fact, the sugar content in these foods is rarely a health concern because they are often packaged with vitamins, minerals, and other protective compounds.

• Fruit and vegetables: Whole fruits contain fructose and glucose, but also fibre, vitamins (like C), minerals, and antioxidants. The fibre in fruit slows digestion and sugar absorption, leading to gradual rises in blood sugar. For example, the University of Nebraska Health Centre notes that “fruit provides many health benefits” – including immune support, a healthy heart, and gut health – despite its sugar content. Similarly, sugars in vegetables and legumes are accompanied by fibre and phytonutrients. Therefore, fruits and vegetables are strongly recommended; U.S. dietary guidelines suggest filling half your plate with them (and they explicitly exclude fresh fruits and vegetables from sugar limits).
• Dairy (milk and yoghurt): Milk contains the natural sugar lactose, plus protein, calcium, and vitamin D (if fortified). Yogurt often contains live cultures as well. The sugar in dairy products is considered natural and provides high-quality nutrition. For most people, including dairy in their diet (as long as it’s not sweetened) is considered healthy, and the sugar content is typically not counted against sugar limits.
• Whole grains and legumes: These contain small amounts of natural sugars, such as maltose, and a high amount of fibre fibre. Whole grains digest more slowly than refined grains, so blood sugar responds less dramatically. Fibre and nutrients in these foods contribute to long-term health, including heart health, digestion, and weight control.

In summary, natural sugars in whole foods are part of a healthy diet because they are accompanied by other nutrients and fibre. The WHO explicitly excludes sugars in fresh fruits, vegetables, and milk from its sugar guidelines, noting that “there is no reported evidence of adverse effects from consuming these sugars.” Eating whole fruits or drinking milk (within calorie limits) is generally considered a health-promoting practice rather than a harmful one.

Key point: Natural sources of sugar (fruits, milk, whole grains) are beneficial. They deliver sugar along with fibre, vitamins, and minerals and have a minimal negative impact on blood sugar. Nutrition experts encourage getting carbohydrates from whole foods rather than sweets.

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Dangers of Excess Sugar

While small amounts of sugar in whole foods are acceptable, excessive sugar—especially added or refined sugar—carries significant health risks. Consuming too much-added sugar can contribute to obesity, diabetes, heart disease, dental problems, and other issues.

• Weight Gain and Obesity: Extra sugar adds “empty” calories. If you take in more calories than you burn, you gain weight. Sugary drinks and snacks are high in calories and easy to overconsume. Both WHO and CDC note that people who consume less sugar generally have lower body weight, while higher sugar intake is associated with weight gain. For instance, the CDC reports that Americans average far above the recommended sugar levels and that “3 in 5 Americans ages 2 and older consume more than the recommended amount of added sugars.” Sugary beverages, in particular, are linked to weight gain: “Consuming too many sugary drinks is associated with weight gain and obesity”.
• Type 2 Diabetes: Diets high in added sugar increase the risk of type 2 diabetes. Chronic sugar consumption contributes to insulin resistance, in which cells fail to respond appropriately to insulin. Over time, this can exhaust the pancreas and lead to blood sugar dysregulation. The CDC lists type 2 diabetes as a consequence of excess sugar intake. Numerous studies confirm that limiting sugar-sweetened beverages and foods helps prevent diabetes.
• Heart Disease and Metabolic Syndrome: Excess sugar can raise triglycerides, lower “good” HDL cholesterol, and increase blood pressure – all risk factors for heart disease. High blood sugar and insulin resistance also contribute to metabolic syndrome. The AHA warns that consuming sugary foods and drinks can contribute to weight gain and blood sugar spikes, which can stress the cardiovascular system. Indeed, reducing sugar intake is often recommended for maintaining heart health.
• Tooth Decay: Sugar feeds the bacteria in your mouth that cause cavities. A high intake of free sugars has been directly linked to an increased risk of dental caries. The WHO notes explicitly that keeping free sugar intake below 10% lowers the risk of tooth decay. The CDC also includes “tooth decay” as a consequence of excessive sugar consumption.
• Other effects: Beyond these significant issues, excessive sugar may contribute to mood swings and energy crashes. Rapid spikes and dips in blood sugar can leave people feeling jittery, followed by fatigue. Some evidence suggests high sugar diets might worsen acne, accelerate skin ageing, and even influence addictive eating behaviours. Chronic overconsumption of sugar can crowd out healthier foods in the diet, potentially leading to nutrient deficiencies.

Key point: Eating a lot of added sugar raises your risk for serious health problems – obesity, type 2 diabetes, heart disease, and cavities. Health organisations categorise excessive sugar consumption as a public health concern. Limiting added sugar intake is crucial for maintaining long-term health.

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Signs You May Need to Cut Back on Sugar

How do you know if you are eating too much sugar? Here are some warning signs:

• Frequent cravings and energy crashes. If you notice intense cravings for sweet foods or drinks and feel “up and down” in energy (short bursts of energy followed by fatigue), excess sugar could be the culprit. After consuming a sugary meal or snack, blood sugar levels often spike and then crash, leaving you tired and craving more sweets.
• Inability to lose weight despite dieting. Sugary foods and drinks contain a high number of calories. If you struggle to lose weight while reducing your fat or carbohydrate intake, consider checking your sugar intake. Hidden sugars in beverages or snacks can sabotage weight-loss efforts. High sugar intake often correlates with unexplained weight gain or a stalled weight-loss plateau.
• Skin and oral health issues. Excessive sugar consumption can exacerbate acne or other skin conditions in some individuals. Additionally, if you have frequent cavities or gum problems, high sugar consumption could be a factor (since sugar promotes tooth decay).
• Elevated blood sugar or prediabetes. Medical signs, such as high fasting blood sugar or A1C levels, indicate that sugar may be too high in your diet. If blood tests show prediabetes, reducing sugar (and refined carbs) is usually recommended.
• High triglycerides or blood pressure. Unhealthy lipid levels or high blood pressure may result from diets high in sugar. If your doctor mentions elevated triglycerides or a risk of metabolic syndrome, cutting added sugar can help.

If you observe any of these signs—especially weight gain, tooth decay, frequent cravings, or lab values trending upward—it may be time to review and reduce your sugar intake.

Key point: Watch for symptoms such as persistent sugar cravings, energy fluctuations, stubborn weight gain, or worsening acne or oral health issues. These can indicate you’re consuming more sugar than is healthy. Cutting back can improve energy, weight, and overall health.

Tips for Healthy Sugar Consumption

You don’t need to eliminate all sugar from your diet, but making mindful choices can make a significant difference. Here are strategies to enjoy sugar safely:

• Choose whole foods. Prioritise fruits, vegetables, whole grains, and dairy products. These foods contain natural sugars, fibre, and nutrients. For a sweet treat, opt for an apple or berries instead of reaching for candy. As the American Heart Association suggests, “Instead of adding sugar to cereal or oatmeal, enjoy the sweetness from the natural sugars found in fruits”. (Try fresh, frozen, or unsweetened canned fruits; avoid those in heavy syrup.)
• Watch beverages. Sugary drinks are a top source of added sugar. Drink water as your first choice. If you crave flavour, try unsweetened tea or sparkling water with fruit slices. The AHA advises replacing sugary sodas with healthier alternatives and recommends water as the best choice. Even coffee or tea should be consumed with little or no added sugar.
• Read labels. Check nutrition facts for “Added Sugars”. The AHA recommends choosing products with the lowest added sugars. Compare brands and opt for unsweetened or low-sugar versions of foods like yoghurt or cereal. Remember: fruit and dairy contain natural sugar, but any form of “syrup,” “maltose,” “fructose,” etc., in ingredient lists indicates added sugar.
• Reduce sugar in recipes. You can cut down on sugar without losing flavour. For example, try cutting the sugar called for in baking recipes by one-third to one-half; often, you won’t notice much difference. Use extracts (such as vanilla, almond, or lemon) or spices (like cinnamon or nutmeg) to enhance sweetness without adding extra sugar. You can also use unsweetened applesauce or mashed banana to partially replace sugar in baking. These small changes can slash sugar in homemade foods.
• Practice portion control. If you have a sugary treat, enjoy a small portion mindfully instead of free-for-all snacking. Sometimes, simply having a dessert portion can reduce intake without feeling deprived. Let your palate adjust over time; gradually, your taste buds will become accustomed to less sweetness.
• Use natural or lower-calorie sweeteners wisely. If you use sweeteners, do so sparingly. AHA mentions low-calorie sweeteners (like stevia or sucralose) as a short-term bridge to reduce sugar, but they should not encourage the overconsumption of sweet flavours. Ideally, train your taste to enjoy foods with less sweetness naturally.
• Balance your meals. Combine carbohydrates with protein, fat, or fibre. This slows sugar absorption and keeps you satisfied. For example, add nuts to fruit, choose yoghurt instead of fruit juice, or have whole-grain toast with nut butter rather than jam.
• Be mindful of “hidden” sugars. Many sauces, such as ketchup and barbecue, breads, and dressings contain sugar. Even some savoury items have added sweeteners. Check labels for unexpected sugars (e.g. “maltose,” “dextrose,” “corn syrup,” “honey,” “fruit juice concentrate”).
• Follow recommendations for children: If you have young children, the Dietary Guidelines recommend no added sugar for children aged 0–2 and minimal sugar for toddlers. Offer whole fruit and milk instead of sugary snacks and drinks.

Implementing these tips can dramatically reduce excess sugar in the diet while still allowing occasional treats. The key is moderation and choosing nutrient-rich sources of carbs.

Key point: Focus on whole foods (fruits, veggies, milk, whole grains), limit sugary beverages, read labels for added sugars, and use clever swaps (fruit for sugar, spices for flavour). Gradually cutting back and being mindful of portions are effective ways to manage sugar intake.

“Track your sugar intake today—your body will thank you!”

FAQs About Sugar and Its Effects on Health