If you're a fan of fizzy drinks, fruit juices and sugary sports drinks, you’re probably not doing your heart any favours.

A new review suggests that regularly quenching your thirst with sugar-sweetened beverages not only contributes to your risk of gaining weight, it also ups your chances of developing type 2 diabetes and metabolic syndrome, a cluster of conditions that raises the risk of heart disease.

“Some studies found that consuming as few as two servings of sugar-sweetened beverages a week was linked to an increased risk of metabolic syndrome, diabetes and heart disease and stroke,” said study senior author Faadiel Essop, a professor at Stellenbosch University.

“Others found that drinking at least one sugar-sweetened beverage per day was associated with elevated blood pressure,” he said, and added that even more alarmingly, some studies found that sugary drinks could raise blood pressure in teenagers.

Metabolic syndrome occurs when you have three or more of the following risk factors for heart disease: abdominal obesity; high levels of triglycerides (a type of blood fat); reduced levels of HDL (the good) cholesterol; elevated blood sugar; and, higher than normal fasting blood sugar levels (but not yet high enough to be considered diabetes), according to the American Heart Association.

The review included 36 studies that looked at the effects of sugary drinks on heart and metabolic health.

READ: These two fizzy drinks may increase risk of diabetes

The studies, which were done within the past 10 years, had varied findings, according to the researchers. But most suggested an association between drinks containing sugar and the development of metabolic syndrome. The majority of studies also looked at people who had more than five sugary drinks a week.

It’s not clear exactly how these drinks increase the odds of metabolic syndrome, Essop said.

But certainly excess consumption of sugary drinks is linked to a higher waist circumference - a factor in metabolic syndrome - and weight gain.

Such drinks have also been tied to decreased insulin sensitivity (a risk for diabetes), inflammation, abnormal cholesterol and high blood pressure, he said.

“Those consuming sugary drinks do not feel as full as those who ate solid foods, even though they had the same amount of calories,” Essop noted, adding that lack of satiety may cause people to eat or drink more.

Dr Joel Zonszein, director of the clinical diabetes centre at Montefiore Medical Centre in New York City, said fruit offered a good example.

“If you eat an apple you get full much easier. In addition to sugar, an apple has a lot of fibre and the satiety is much better. But when you have a glass of apple juice, you’re getting the sugar from three to four apples and no fibre. That’s a much more concentrated dose of sugar that will spike the blood sugar level,” he said.

Dr William Cefalu, chief scientific, medical and mission officer from the American Diabetes Association, said the studies included in this review were observational studies, which are a good starting point when looking at medical problems, but they could not prove a cause-and-effect relationship.

“What we can be sure of, however, is that sugar-sweetened beverages provide a substantial amount of excess calories with no nutritional benefit, and excess calories beyond what is normally needed by the body to maintain normal activities, in turn, does lead to weight gain.”

And excess weight is a significant risk factor for type 2 diabetes, as well as many heart disease risk factors.

“Drinking water is the best form of hydration for all people - with or without diabetes,” he said.

One important exception, Cefalu noted, is anyone with diabetes (particularly if treated with insulin) whose blood sugar is low. In that case, it’s crucial to quickly raise blood sugar levels to prevent serious complications.

A sugar-sweetened beverage such as juice or soda can do that quite well. - New York Times