Yes. Added sugar drives weight gain and obesity. It is high in empty calories. It raises blood sugar until insulin resistance (when cells stop answering insulin) sets in. And it is less filling, so you eat more. A review of 30 studies in more than 242,000 adults and children found a significant link between sugar-sweetened drinks and obesity.
Sugar has been blamed for years for doing great harm to our health. Are these claims true? Does a soda a day guarantee ill health? What does too much sugar do to obesity? Here we look at these claims. We ask whether too much sugar really leads to obesity.
1. What is obesity?
Obesity rates have skyrocketed over the past century. In 1962, 46 percent of adults in the U.S. were considered overweight or obese. By 2010, that figure had jumped to 75 percent. So, what exactly is obesity? Obesity is a complex disease. It means having too much body fat. Obesity isn’t just about looks. It is a medical problem. It raises your risk of other diseases and health problems, such as heart disease, diabetes, high blood pressure and certain cancers. Obesity is diagnosed when your body mass index (BMI) is 30 or higher. To find your body mass index, divide your weight in pounds by your height in inches squared. Then multiply by 703. Or divide your weight in kilograms by your height in meters squared.
| BMI | Weight status |
| Below 18.5 | Underweight |
| 18.5-24.9 | Normal |
| 25.0-29.9 | Overweight |
| 30.0 and higher | Obesity |
For most people, BMI gives a fair estimate of body fat. But BMI doesn’t measure body fat directly. So some people, such as muscular athletes, may have a BMI in the obesity range even though they don’t carry extra body fat.
2. Sugar and obesity
Obesity is a complex problem with many causes. But among the likely suspects, sugar is a top favorite. As sugar intake has gone up, so has the size of our waistlines. Added sugars are a hotly debated topic. Eating added sugars has been tied to higher risk of a variety of chronic diseases. These include obesity, heart and blood vessel disease, diabetes and non-alcoholic fatty liver disease (NAFLD). They also include mental decline and even some cancers. Still, support for these possible links has been challenged on several fronts. The sugars in your diet can be either naturally occurring or added. Naturally occurring sugars are found naturally in foods such as fruit (fructose) and milk (lactose). Added sugars are sugars and syrups put in foods while they are made or processed, or added at the table. Many eating and lifestyle habits can lead to weight gain and extra body fat. Take a diet high in added sugars, such as sweetened drinks, candy, baked goods, and sugary cereals. It is a contributing factor in weight gain and chronic health problems, including obesity, heart disease, and diabetes. Many people eat more sugar than they realize. It’s important to know how much sugar you eat, because our bodies don’t need sugar to work properly. Added sugars give zero nutrients but many added calories. That can lead to extra pounds or even obesity, which hurts our health. The ways added sugar leads to weight gain and more body fat are complex and involve many factors.
3. Some ways added sugar is fattening
- It is high in empty calories Added sugars are sweeteners added to foods and drinks to improve taste. Common types of added sugar include fructose, corn syrup, cane sugar, and agave. Excess sugar may cause you to pack on weight. This is because it’s high in calories but offers few other nutrients. Small amounts of added sugar are unlikely to cause weight gain. But eating foods high in added sugars on a regular basis may cause you to gain extra body fat faster and more sharply.
- Impacts blood sugar and hormone levels
It’s well known that eating sugary foods significantly raises your blood sugar. A sweet treat now and then isn’t likely to harm your health. But eating large amounts of added sugar every day can lead to blood sugar that stays high. Blood sugar that stays high for a long time is called hyperglycemia. It can cause serious harm to your body. It does this by causing insulin resistance, which results in weight gain.
- May lead to overeating
Foods high in added sugars tend to be less filling. Some foods are rich in carbs, mostly refined carbs high in added sugars, yet low in protein. They can hurt fullness and may lead to weight gain. They do this by causing you to eat more at later meals during the day, or to overeat at any one particular sitting. Animal studies indicate that fructose affects signals in your hypothalamus (the brain’s hunger center). It raises hunger-boosting neuropeptides. These are molecules that talk to one another and shape brain activity. At the same time, it lowers fullness signals. Also, your body is built to crave sweetness. In fact, research shows that we eat sugar for the pleasure of the sweet taste of sugary drinks and foods.
- Linked to obesity and chronic disease
Many studies have linked high intake of added sugars to weight gain and chronic conditions, such as obesity, heart disease, and diabetes. This effect has been seen in both adults and children. Recently, a review of 30 studies in more than 242,000 adults and children found a significant link between sugar-sweetened drinks and obesity.
4. What are some of the health problems associated with obesity?
People with obesity are more likely to develop a number of potentially serious health problems, including:
- Heart disease and strokes. Obesity makes you more likely to have high blood pressure and abnormal cholesterol levels. These are risk factors for heart disease and strokes.
- Type 2 diabetes. Obesity can affect the way your body uses insulin to control blood sugar levels. This raises your risk of insulin resistance and diabetes.
- Certain cancers. Obesity may increase your risk of cancer of the uterus, cervix, endometrium, ovary, breast, colon, rectum, esophagus, liver, gallbladder, pancreas, kidney and prostate.
- Digestive problems. Obesity makes you more likely to get heartburn, gallbladder disease and liver problems.
- Gynecological and sexual problems. Obesity may cause infertility (trouble getting pregnant) and irregular periods in women. Obesity also can cause erectile dysfunction in men.
- Sleep apnea. People with obesity are more likely to have sleep apnea. It is a potentially serious problem in which breathing stops and starts again and again during sleep.
- Osteoarthritis. Obesity raises the stress on weight-bearing joints. It also promotes inflammation in the body. These factors may lead to problems such as osteoarthritis.
Why Is Sugar Bad For Your Health? covers how sugar also drives inflammation, heart disease, kidney disease and gout.
5. How can obesity affect your quality of life?
People who are obese often struggle with some issues that might lower their quality of life. Some of these issues might include:
- Depression
- Disability
- Sexual problems
- Shame and guilt
- Social isolation
- Lower work achievement
6. How can you keep yourself from getting obese?
Maybe you’re at risk of obesity. Maybe you are overweight now, or at a healthy weight. Either way, you can take steps to prevent unhealthy weight gain and the health problems that come with it.
- Exercise regularly. You need 150 to 300 minutes of moderate activity a week to prevent weight gain. Moderate activities include fast walking and swimming.
- Follow a healthy-eating plan. Focus on low-calorie, nutrient-dense foods, such as fruits and vegetables, along with red meat and fish. Skip refined grains, and limit sweets and alcohol. Eat three regular meals a day with limited snacking. You can still enjoy small amounts of high-fat, high-calorie foods as an infrequent treat.
- Know and avoid the food traps that cause you to eat. Find the situations that set off out-of-control eating. Try keeping a journal. Write down what you eat, how much you eat, when you eat, how you’re feeling and how hungry you are. This helps you stay in control of your eating.
- Monitor your weight regularly. People who weigh themselves at least once a week do better at keeping off extra pounds.
- Be consistent. Stick to your healthy-weight plan all the time.
7. So, is sugar friend or foe?
Added sugars mess with your hormones, raise hunger, and push out healthy foods. These are just a few of the ways they can lead to weight gain. Too much added sugar also does more than add body fat. It can significantly raise your risk of chronic conditions, such as obesity, heart disease, and diabetes. So it is wise to eat added sugars with caution, because a stitch in time saves nine.
The mechanism is covered in Understanding The Role Of Metabolic Inflammation Plays In Obesity And Diabesity.
Related reading
References
- Endocrineweb (2018): Insulin Resistance Causes and Symptoms, Retrieved from
https://www.endocrineweb.com/conditions/type-2-diabetes/insulin-resistance-causes-symptoms
- Healthline (2019): 6 Ways Added Sugar Is Fattening. Retrieved from
https://www.healthline.com/nutrition/does-sugar-make-you-fat#section1
- American Heart Association (2018): Added Sugars. Retrieved from
https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sugar/added-sugars
- NCBI (2016): Relationship between Added Sugars Consumption and Chronic Disease Risk Factors: Current Understanding. Retrieved from
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5133084/
- Johns Hopkins Medicine (2019): Obesity, Sugar and Heart Health. Retrieved from
https://www.hopkinsmedicine.org/health/wellness-and-prevention/obesity-sugar-and-heart-health
- Mayo Clinic: Retrieved from
https://www.mayoclinic.org/diseases-conditions/obesity/symptoms-causes/syc-20375742
Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP
Interventional pain physician, addiction medicine specialist and obesity medicine diplomate.
Licensed in Missouri and Illinois.
Last reviewed June 18, 2026
