We should eat food from the five food groups every day, we should avoid added salt and sugar, we should limit alcohol, and we should be physically active. We know all that, don't we? Well, the esteemed National Health and Medical Research Council has just released draft national dietary guidelines after what it describes as the world's most comprehensive investigation of the subject, and the old chestnuts above pretty well sum them up. As well, there's a guideline to encourage breastfeeding and another to prepare and store food safely, which suggests that the NHMRC thinks we're all dills.

Certainly it thinks that most of us are overweight, and certainly it is right. The proportion of overweight Australians has increased dramatically, it says, to the point that 62 per cent of us are now officially overweight. Its other figures are compelling - poor diet is to blame for 16 per cent of disease in Australia and is implicated in 56 per cent of deaths. The problem is diet, before even exercise, but guidelines recommending a daily diet that draws from the five food groups are simply more of the same. Is an obese or merely overweight person going to read this and, blink, see the light? Will it be news to any of their doctors and other advisers? No and no.

The problem is, I believe, that it is easier and cheaper to eat badly in Australia, and it has been that way for so long that a great many Australians will find change too difficult. They will find healthy food strangely unsatisfying, and many won't have a clue how to prepare it. Salad is an example of this. People who are not accustomed to eating salad refer to it disparagingly as rabbit food and it seems that nothing would entice them to eat it.

I don't think Australia will so much as halt the annual increase in its weight problem until our governments take aggressive, and brave, moves to reshape the national diet. Changing diet will require the same confronting approach used by government to tackle smoking, and tax was an important weapon in that war. Tax could be used to make unhealthy foods, such as takeaway and sugar-laden drink, considerably more expensive and, perhaps, to reduce the cost of healthy food. It appears to me that sugar-laden soft drink, certainly the most efficient means of delivering excessive quantities of sugar, is as much a threat to some people's health as tobacco is to others', yet it is often cheaper than bottled water and always cheaper than milk. Should, for example, a bottle of soft drink carry a photo of an obese person, in briefs? Do you need more dietary guidelines? Should we get tough on fat and sugar?