People are underestimating sugar levels in drinks which are perceived to be "healthy" options, according to new research.
More than 2,000 people across the UK were asked to estimate how many teaspoons of sugar were in a variety of beverages and, while many overestimated the amount in fizzy drinks, they "significantly misjudged" the levels in milkshakes, smoothies and some fruit juices.
The research, carried out by the University of Glasgow, suggested the average person in the UK consumes 659g and 3,144 calories a week through non-alcoholic liquid intake. At 450 calories a day, it is the equivalent to almost a quarter of the recommended daily calorie intake for women and around a fifth for men.
Half of people who admitted to drinking three or more sugary drinks in a day said they did not compensate by reducing the calorie intake of their food while nearly a quarter of those surveyed did not take into consideration their liquid sugar or calorie intake when they were last on a diet.
The over-consumption of sugar-sweetened drinks contributes to obesity, which is a major risk factor for health conditions such as type-2 diabetes, high blood pressure and heart disease and stroke.
Naveed Sattar, professor of metabolic medicine at the university, said: "What you drink can be as damaging to the body as what you eat and there is no question that consuming too many sugar-sweetened drinks can greatly contribute to abdominal obesity and, therefore, increase your likelihood of developing health conditions such as type-2 diabetes and cardiovascular disease.
Sasha Watkins, a registered dietitian and British Dietetic Association spokesperson, told HuffPost Lifestyle:
"The results from this study do sound plausible. Other research suggests that it may be harder for us to regulate the intake of calories we drink and there appears to be a positive association between a greater consumption of sugar sweetened drinks and weight gain in both adults and children.
"Fruit juice is still a better choice than a soft drink as it also contains vitamins and minerals but dietitians recommend that only one glass of 150ml unsweetened 100% fruit or vegetable juice can count towards your 5 a day. This is because when whole fruit and vegetables are juiced all the fibre is removed. Fruit juice may also cause tooth decay.
Visualising the amount of sugar in your drinks can be hard, Watkins points out, because most people don't read food labels.
"A can of Coca Cola may contain up to 7 teaspoons of sugar but few people would add 7 teaspoons of sugar to their tea! People would be shocked by the amount of added sugar in some soft drinks," she says.
"There should be a call for standard food labelling. If people don't know how to read labels, how can they make informed decisions about how much sugar is in their drinks?"
However, the British Soft Drinks Association deny that current labelling is insufficient.
In a statement, the industry body said: "The sugar in soft drinks is clearly labelled and most drinks do not contain sugar. It is not the case that sugar in soft drinks is 'hidden'.
"Nutritional information, including calorie content and sugar content, is stated in a clear format on the front of the pack. The Guideline Daily Amounts (GDAs) format enables consumers easily to compare one product with another and choose the one most suitable for their diet."