For a while, nutritional orthodoxy has been gradually swinging around to the opinion that sugar, rather than fat, is public enemy number one in the fight against diseases of affluence that are increasingly affecting developed societies such as Hong Kong.
But while it's hard not to know that sugar's bad for you, particularly in excessive quantities, it can be equally difficult to work out precisely how much is too much. It can also be hard to judge just how much we're having, something that's particularly true when we're swigging down sugar-laden soft drinks. Because of this, some have suggested that sugary drinks should carry health warnings similar to those on cigarette packets.
In the US, the California state legislature is considering a bill that would mandate such warnings, with the proposed text reading: "State of California safety warning: drinking beverages with added sugar(s) contributes to obesity, diabetes, and tooth decay."
Opinion polls indicate that the bill is supported by about three-quarters of Californians, while similar opinion polls in other Western countries show that a majority of people would back such health warnings. The view has support from the medical establishment, too, with a recent article appearing in the British Medical Journal , written by Simon Capewell, professor in the department of public health and policy at Britain's University of Liverpool. Such a view doesn't have much support in Hong Kong and suggests how far we might have to shift in the future, given our relatively relaxed requirements on nutritional labelling and the fact that 36.6 per cent of Hongkongers aged between 18 and 64 are overweight or obese, according to figures published last year by the Centre for Health Protection.
Sugary drinks are a particular problem because people can consume a lot without feeling full. Chilling and carbonation make these drinks seem less sweet, as anyone who's drunk a warm and flat one will know.
"They only provide energy, no other nutritional value," says Verona Tam, a registered dietitian who is on the Hong Kong Nutrition Association's continuing education subcommittee. "Sugar from drinks is absorbed quite easily, so you don't feel full. And a higher intake of sugar is usually associated with a higher energy intake and lower diet quality."
A study by the Hong Kong government found that people who drink a can or more of sugary drink a day have a 26 per cent greater chance of developing type 2 diabetes than people who drink none or almost none. That figure was 22 per cent in a similar survey carried out in Europe, where diabetes is becoming a real problem.
This has worrying implications, particularly for China. In addition to diabetes, sugar is a factor in cardiovascular disease and some of the most common cancers.
The World Health Organisation says that sugar should account for no more than 10 per cent of total energy intake, but recommends that people try to get that down to 5 per cent. Based on a 2,000-calorie-a-day diet, 10 per cent is about 50g a day. A 330ml can of soft drink contains more than half that. The leading cola brands both contain just over 10g of sugar per 100ml, which equates to about nine teaspoons. Many other beverages, from sports drinks to green tea drinks, fall within the 7g-12g per 100ml range, but some run as high as 15g.
Hong Kong's nutritional labelling laws only require manufacturers to indicate the quantity of sugar in grams, with no indication of how much is too much or even of what the number of grams actually equates to.
"The sugar content on the package doesn't translate into anything very realistic," says Karen Chong, registered dietitian at the Matilda International Hospital. "As a layman, you don't know what 5g or 10g of sugar is."
One option would be to translate that figure into the equivalent number of spoonfuls. Another would be a percentage of the daily value or RDA, which is already used in a lot of countries, but that's an approximation based on a 2,000-calorie-a-day diet that is only accurate for a handful of people.
Complicating the business of working out how much sugar is in your drink is the fact that these figures are usually expressed on the label as per serving (usually per 100ml), rather than for the entire drink.
Labelling and public health campaigns have been effective around the world in reducing the consumption of alcohol and tobacco, and there are precedents globally for unhealthy food warnings.
Finland has long indicated which foods are high in salt, which is a particular danger in the Scandinavian diet, while Britain employs a so-called traffic light system that indicates potentially dangerous levels of salt, saturated fat and sugar.
Chong says that with other issues of public nutrition policy, such as trans fats, Hong Kong has not enacted bans or other restrictions, whereas many other jurisdictions have. The same is likely to remain true for the labelling of sugar.
"I am not sure that putting health warnings on drinks will have a huge effect in discouraging people from drinking sugary beverages," says Tam. "There are a lot of tobacco warnings in Hong Kong, but do people who are regular smokers stop smoking after they see them? Perhaps, but not to a great extent."
With tobacco, price increases seem to have worked better than health warnings. But Tam says the immediate priority should be education. "Most important is to learn how to read the nutrition label. I think the best way to discourage people is through education, starting as young as possible."
Labelling aside, the government, which recommends consumption of less than 50g of sugar a day, has offered information about the dangers of sugar in drinks.
The Centre for Food Safety has produced a fact sheet in collaboration with the Hong Kong Nutrition Association as part of its NutriGet series about how to interpret the labelling on sugary drinks.
It has been distributed in housing estates, hospitals, schools, non-governmental organisations and government departments including Home Affairs Department offices, Department of Health clinics and Social Welfare Department service centres. It has also been used in exhibitions, workshops and seminars organised by the Centre for Food Safety. It lists sugar levels in popular drinks, provides information about how to interpret the label, details the health risks and suggests alternatives.
One alternative that is commonly considered healthier is fruit juice, but it can often contain large quantities of fructose, which is no less dangerous in excess. Chong, though, says that it's still an improvement. "Comparing sugary drinks, I'd rather you had fresh juice than a fizzy drink [as] it also contains vitamins, minerals and antioxidants."
But, she adds, as a dietitian she'd always suggest that people eat the whole fruit rather than juice accompanied by a cup of unsweetened tea, or a glass of water.