When consumed in excess, added sugar can adversely affect your health.
However, some sources of sugar are worse than others — and sugary drinks are by far the worst.
This primarily applies to sugary soda but also to fruit juices, highly sweetened coffees, and other sources of liquid sugar.
Here are 13 reasons that sugary soda is bad for your health.
The most common form of added sugar — sucrose or table sugar — supplies large amounts of the simple sugar fructose.
Thus, when you consume liquid sugar, you usually add it on top of your total calorie intake — because sugary drinks don’t make you feel full (, , ).
In one study, people who drank sugary soda in addition to their current diet consumed 17% more calories than before ().
Not surprisingly, studies show that people who drink sugar-sweetened beverages consistently gain more weight than people who don't (, , ).
In one study in children, each daily serving of sugar-sweetened beverages was linked to a 60% increased risk of obesity ().
In fact, sugary drinks are among the most fattening aspects of the modern diet.
SUMMARY You tend to consume more total calories if you drink soda, as liquid sugar doesn’t make you feel full. Sugar-sweetened beverages are associated with weight gain.
Table sugar (sucrose) and high-fructose corn syrup are composed of two molecules — glucose and fructose — in roughly equal amounts.
Glucose can be metabolized by every cell in your body, whereas fructose can only be metabolized by one organ — your liver ().
Sugary drinks are the easiest and most common way to consume excessive amounts of fructose.
When you consume too much, your liver becomes overloaded and turns the fructose into fat ().
SUMMARY Sucrose and high-fructose corn syrup are about 50% fructose, which can only be metabolized by your liver. Excessive amounts may contribute to nonalcoholic fatty liver disease.
High sugar intake is associated with weight gain.
In particular, fructose is linked to a significant increase in the dangerous fat around your belly and organs. This is known as visceral fat or belly fat ().
Excessive belly fat is tied to an increased risk of type 2 diabetes and heart disease (, ).
In one 10-week study, 32 healthy people consumed beverages sweetened with either fructose or glucose ().
Those who consumed glucose had an increase in skin fat — which is not linked to metabolic disease — while those who consumed fructose saw their belly fat significantly increase.
SUMMARY High consumption of fructose makes you accumulate belly fat, a dangerous type of fat linked to metabolic disease.
The hormone insulin drives glucose from your bloodstream into your cells.
But when you drink sugary soda, your cells may become less sensitive or resistant to the effects of insulin.
When this happens, your pancreas must make even more insulin to remove the glucose from your bloodstream — so insulin levels in your blood spike.
This condition is known as insulin resistance.
Insulin resistance is arguably the main driver behind metabolic syndrome — a stepping stone towards type 2 diabetes and heart disease ().
Animal studies demonstrate that excess fructose causes insulin resistance and chronically elevated insulin levels (, , 22).
One study in healthy, young men found that moderate intake of fructose increased insulin resistance in the liver ().
SUMMARY Excess fructose intake may lead to insulin resistance, the main abnormality in metabolic syndrome.
Type 2 diabetes is a common disease, affecting millions of people worldwide.
It is characterized by elevated blood sugar due to insulin resistance or deficiency.
Since excessive fructose intake may lead to insulin resistance, it is unsurprising that numerous studies link soda consumption to type 2 diabetes.
In fact, drinking as little as one can of sugary soda per day has been consistently linked to an increased risk of type 2 diabetes (, , , ).
A recent study, which looked at sugar consumption and diabetes in 175 countries, showed that for every 150 calories of sugar per day — about 1 can of soda — the risk of type 2 diabetes increased by 1.1% ().
To put that in perspective, if the entire population of the United States added one can of soda to their daily diet, 3.6 million more people might get type 2 diabetes.
SUMMARY A large body of evidence links added sugar consumption — particularly from sugar-sweetened beverages — to type 2 diabetes.
Sugary soda contains virtually no essential nutrients — no vitamins, no minerals, and no fiber.
It adds nothing to your diet except excessive amounts of added sugar and unnecessary calories.
SUMMARY Sugary sodas contain little to no essential nutrients, only providing sugar and calories.
Leptin is a hormone produced by your body's fat cells. It regulates the number of calories you eat and burn (, , ).
Leptin levels change in response to both starvation and obesity, so it’s often called the fullness or starvation hormone.
Being resistant to this hormone's effects — referred to as leptin resistance — is now believed to be among the leading drivers of fat gain in humans (32, ).
In fact, animal research links fructose intake to leptin resistance.
In one study, rats became leptin resistant after being fed large amounts of fructose. Strikingly, when they reverted back to a sugar-free diet, leptin resistance disappeared (, ).
That said, human studies are needed.
SUMMARY Animal trials suggest that a high-fructose diet can drive leptin resistance. Eliminating fructose may reverse the problem.
It’s possible that sugary soda is an addictive substance.
In rats, sugar binging may cause dopamine release in the brain, giving a feeling of pleasure (36).
Binging on sugar may have similar effects in certain people, as your brain is hardwired to seek out activities that release dopamine.
In fact, numerous studies suggest that sugar — and processed junk foods in general — affect your brain like hard drugs ().
For individuals predisposed toward addiction, sugar may cause reward-seeking behavior known as food addiction.
Studies in rats demonstrate that sugar can be physically addictive (, , ).
While addiction is harder to prove in humans, many people consume sugary drinks in a pattern typical for addictive, abusive substances.
SUMMARY Sugary drinks have powerful effects on your brain's reward system, which may lead to addiction.
Sugar intake has long been linked to heart disease risk (, ).
It is well established that sugar-sweetened drinks increase risk factors for heart disease, including high blood sugar, blood triglycerides, and small, dense LDL particles (, ).
Recent human studies note a strong association between sugar intake and heart disease risk in all populations (, , , , , ).
One 20-year study in 40,000 men found that those who drank 1 sugary drink per day had a 20% higher risk of having — or dying from — a heart attack, compared to men who rarely consumed sugary drinks ().
SUMMARY Multiple studies have determined a strong link between sugary beverages and heart disease risk.
Cancer tends to go hand-in-hand with other chronic diseases like obesity, type 2 diabetes, and heart disease.
For this reason, it is unsurprising to see that sugary drinks are frequently associated with an increased risk of cancer.
One study in over 60,000 adults discovered that those who drank 2 or more sugary sodas per week were 87% more likely to develop pancreatic cancer than those who did not drink soda ().
Another study on pancreatic cancer found a strong link in women — but not men ().
Postmenopausal women who drink a lot of sugary soda may also be at greater risk for endometrial cancer, or cancer of the inner lining of the uterus ().
What’s more, sugar-sweetened beverage intake is linked to cancer recurrence and death in patients with colorectal cancer ().
SUMMARY Observational studies suggest that sugar-sweetened beverages are linked to an increased risk of cancer.
It is a well-known fact that sugary soda is bad for your teeth.
Soda contains acids like phosphoric acid and carbonic acid.
These acids create a highly acidic environment in your mouth, which makes your teeth vulnerable to decay.
While the acids in soda can themselves cause damage, it is the combination with sugar that makes soda particularly harmful (, ).
Sugar provides easily digestible energy for the bad bacteria in your mouth. This, combined with the acids, wreaks havoc on dental health over time (, ).
SUMMARY The acids in soda create an acidic environment in your mouth, while the sugar feeds the harmful bacteria that reside there. This can have severe adverse effects on dental health.
Gout is a medical condition characterized by inflammation and pain in your joints, particularly your big toes.
Gout typically occurs when high levels of uric acid in the blood become crystallized ().
Fructose is the main carbohydrate known to increase uric acid levels ().
Consequently, many large observational studies have determined strong links between sugar-sweetened drinks and gout.
Moreover, long-term studies tie sugary soda to a 75% increased risk of gout in women and an almost 50% increased risk in men (, , ).
SUMMARY People who frequently down sugary drinks appear to have an increased risk of gout.
Dementia is a collective term for declines in brain function in older adults. The most common form is Alzheimer's disease.
In other words, the higher your blood sugar, the higher your risk of dementia.
Because sugar-sweetened beverages lead to rapid spikes in blood sugar, it makes sense that they could increase your risk of dementia.
SUMMARY Some studies indicate that high blood sugar levels raise your risk of dementia.
Drinking high amounts of sugar-sweetened beverages — such as soda — can have various adverse impacts on your health.
These range from increased chances of tooth decay to a higher risk of heart disease and metabolic disorders like type 2 diabetes.
Regular consumption of sugary soda also appears to be a consistent risk factor for weight gain and obesity.