When consumed in excess, added sugar can have disastrous effects on your health.
However, some sources of sugar are worse than others... and sugary drinks are the worst, by far.
This primarily applies to sugary soda, but also to fruit juices, highly sweetened coffees and other sources of liquid sugar.
Here are 13 reasons to avoid soda (and other sugary drinks) like the plague.
Added sugar is highly fattening... and liquid sugar even more so.
One of the reasons for this, is that sugar supplies large amounts of the simple sugar fructose, which does not lower the hunger hormone ghrelin in the same way as glucose, the main carb found in starchy foods ().
Studies have also shown that fructose does not seem to stimulate the satiety centers in the brain in the same way as glucose ().
The brain is actually supposed to regulate your calorie intake. If you eat more of one food (like potatoes), you should automatically eat less of something else instead.
Liquid sugar doesn't work in this way... when people consume it, they usually add it on top of the total calorie intake ().
In other words, sugary drinks don't make you feel full, so you eat the same amount of food as before, but with a whole lot of extra sugar calories on the side (, ).
In one study, people who added soda on top of their current diet ended up consuming 17% more calories than before. That is a huge amount, which could easily lead to obesity over a few years ().
Not surprisingly, studies have shown 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 ().
The truth is... sugary drinks are THE most fattening aspect of the modern diet. If you want to lose weight, or avoid gaining it over time, then you should seriously consider removing these drinks from your life.
Bottom Line: Liquid sugar does not cause satiety in the same way as solid foods, making people eat more total calories. Sugar-sweetened beverages may be the most fattening aspect of the modern diet.
Sugar is composed of two molecules... glucose and fructose.
Glucose can be metabolized by every cell in the body, whereas fructose can only be metabolized by one organ, the liver ().
Sugary drinks are the easiest (and most common) way to consume excessive amounts of fructose.
When we consume too much, in the context of a high-carb, high-calorie Western diet, the liver becomes overloaded and turns the fructose into fat ().
Some of the fat gets shipped out as blood triglycerides, while part of it remains in the liver. Over time, this can contribute to non-alcoholic fatty liver disease ( ).
Bottom Line: Sucrose and high fructose corn syrup are about 50% fructose, which can only be metabolized by the liver. Excessive amounts may contribute to non-alcoholic fatty liver disease.
Sugar consumption makes you prone to storing more body fat.
Fructose in particular appears to dramatically increase the dangerous fat around the belly and organs. This is known as visceral fat, or belly fat ().
In a 10 week study, 32 healthy people consumed beverages sweetened with either fructose or glucose ().
Glucose consumers only had an increase in subcutaneous fat (not linked to metabolic disease), while fructose drinkers had a significant increase in the harmful visceral fat.
Bottom Line: High consumption of fructose causes accumulation of visceral fat, the dangerous fat that leads to metabolic disease.
The main function of the hormone insulin, is to drive glucose from the bloodstream into cells.
But when we drink sugary soda, the cells tend to become resistant to the effects of insulin.
When this happens, the pancreas must make even more insulin to remove the glucose from the bloodstream, so insulin levels in the blood go up.
This condition is known as insulin resistance.
Insulin resistance is arguably the main driver behind , a stepping stone towards type 2 diabetes and heart disease ().
Excess sugar is a known cause of insulin resistance and chronically elevated insulin levels in the blood ( ).
Bottom Line: Excess sugar can lead to insulin resistance, the main abnormality in metabolic syndrome.
Type 2 diabetes is a very common disease, affecting about 300 million people worldwide.
It is characterized by elevated blood sugars in the context of insulin resistance or a deficiency in insulin.
Given that sugary drinks can lead to insulin resistance, it is not surprising to see that numerous studies link soda consumption with type 2 diabetes.In fact, as little as one can of soda per day has been consistently linked to an increased risk of type 2 diabetes (, , , ).
In a recent study looking at sugar consumption and diabetes in 175 countries, each 150 calories (about one can of soda) of sugar per day was linked to a 1.1% increase in type 2 diabetes ().
To put that number in perspective, if the entire US population added one can of soda to their daily diet, almost 3.5 million people might become diabetic.
Bottom Line: There is a large body of evidence linking added sugar consumption, particularly from sugar-sweetened beverages, to type 2 diabetes.
Sugary soda is "empty" calories. No doubt about that.
It contain absolutely no essential nutrients... no vitamins, no minerals, no antioxidants and zero fiber.
It literally adds nothing to the diet except excessive amounts of added sugar and unnecessary calories.
Bottom Line: Sugary sodas contain little to no essential nutrients and can therefore be classified as "empty" calories.
Leptin is a hormone that is produced by the body's fat cells ().
Its main role is long-term regulation of energy balance... dictating the number of calories we eat and burn (, ).
Leptin is supposed to protect us from both starvation and obesity, and is often referred to as the "satiety hormone" or the "starvation hormone."
Being resistant to this hormone's effects (called leptin resistance) is now believed to be among the leading drivers of fat gain in humans (, ).
Well... several preliminary studies have linked sugar intake, primarily fructose, to leptin resistance in rats.
When these rats were fed large amounts of fructose, they became leptin resistant. When they reverted back to a sugar-free diet, leptin resistance went away (, ).
However, this is far from definitive and needs to be confirmed in human studies that use physiologically relevant doses of sugar. These rat studies used massive doses, as in up to 60% of calories as fructose.
Bottom Line: Animal studies show that a high fructose diet can drive leptin resistance, but eliminating fructose reverses the problem.
When we eat sugar, dopamine is released in the brain, giving us a feeling of pleasure ().
The human brain is hardwired to seek out activities that release dopamine. Activities that releases huge amounts are especially desirable.
This is actually how addictive drugs like cocaine function, and the reason people can become dependant on them.
Well... numerous studies suggest that sugar, and processed junk foods in general, can have similar effects ().
For certain people with a predisposition to addiction, this causes reward-seeking behavior typical of addiction to abusive drugs. This is also 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 (and other junk foods) in a pattern that is typical for addictive, abusive substances.
Bottom Line: Sugary drinks have powerful effects on the brain's reward system, which can cause downright addiction in susceptible individuals.
Sugar intake was first linked to heart disease risk back in the 60's and 70's (, ).
Since then, it has been established that sugar-sweetened drinks increase some of the main risk factors for cardiovascular disease.
This includes blood sugar, blood triglycerides, small, dense LDL particles and numerous others (, ).
More recent studies in humans have found strong links between sugar intake and heart disease risk in men, women and adolescents (, , , , , ).
One study following 40,000 men for two decades found that those who drank one sugary drink per day had a 20% higher risk of having a heart attack, or dying from a heart attack, compared to men who rarely consumed sugary drinks ().
Bottom Line: The relationship between sugar and heart disease risk was first discovered decades ago. Since then, many studies have found strong links.
The risk of cancer tends to go hand-in-hand with other chronic diseases like obesity, type 2 diabetes and heart disease.For this reason, it is not surprising to see that sugary drinks are frequently associated with an increased risk of cancer.
One study of over 60,000 men and women found that those who drank two 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 with high intakes of sugary soda also appear to be at greater risk for cancer in the inner lining of the uterus, called endometrial cancer ().
Sugar-sweetened beverage consumption has also been linked to cancer recurrence and death in patients with colorectal cancer ().
Bottom Line: There is evidence from observational studies that consumption of sugar-sweetened beverages is 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 the mouth, which makes the 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 the mouth. This, combined with the acids, wreaks havoc on dental health over time (, ).
Bottom Line: The acids in soda cause an acidic environment in the 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 the joints, particularly the large 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 found strong links between sugar-sweetened drinks and gout.
Long-term studies have shown that sugary soda is linked to a 75% increased risk of gout in women, and almost a double risk in men (, , ).
Bottom Line: Men and women who frequently drink sugary drinks appear to have an increased risk of developing gout.
Dementia is the collective term used to describe neurodegenerative conditions that can occur as we grow older.
The most common form is Alzheimer's disease.
Research has found that any incremental increase in blood sugar is strongly associated with an increased risk for dementia (, ).
In other words, the higher your blood sugar, the higher the risk of dementia.
Because sugar-sweetened beverages lead to rapid spikes in blood sugars and can raise blood sugar by causing insulin resistance, it makes sense that they could increase your risk of dementia.
Rodent studies , showing that large doses of sugary drinks can impair memory and decision-making capabilities ().
So... not only do sugary drinks wreak havoc on metabolic health, they appear to be seriously harmful for your brain as well.
If you want to lose weight, avoid chronic disease and live longer with a sharper brain, then consider avoiding sugary drinks like the plague.