The new obesity strategy is a first for Gordon Brown's government - perhaps for any government - in finally acknowledging the complexity of the issue and trying to work out a joined up approach to solving the problem. This is thanks, in no small part, to the Foresight Report's extensive analyses and the further work of an expert group providing essential insights into what might be done to avert the public heath disaster that all agree is looming large.

While the health service bears the burden of obesity and related diseases that are already becoming a major drain on its resources, it is other arms of government that shape the environment in which obesity thrives. As Gordon Brown declared: "We must do nothing less than transform the environment in which we all live."

Of course it is far easier said than done. The commitment to become the first major country to reverse the obesity trend is a bold pledge that will be difficult to redeem. But the target of restoring childhood overweight and obesity prevalence to year 2000 levels by 2020 sets a questionable performance benchmark against which to test this promise. Success on these terms means still having more than one quarter of youngsters overweight - half of whom will be obese. The conveyor belt will still be whirring away.

Yet the focus on children is essential, and halting the so-called conveyor-belt effect - perhaps escalator would be a better analogy - is an all-important goal. But obesity rates will need to drop far below year 2000 levels to achieve the desired "knock-on" effect in eventually reducing obesity among future adults.

The present approach implies we must be resigned to having higher levels of obesity for some time to come - with the Foresight forecast of a 35% rise in type-2 diabetes by 2020 inevitably fulfilled. Meanwhile the rest of the population must spring into action, with a level of response never before seen in public health without supporting regulations. Smoking is a recent example and the clunk click of car seat belts is an earlier case where most people resist common sense behaviour until they are obliged to toe the line and social norms are transformed.

Shaping the environment is one of the tougher nuts that the new strategy sets out to crack. Building new "healthy towns" and introducing health impact into planning considerations are welcome departures; using planning criteria to restrict the over-provision of fast food restaurants around schools is a useful long-term strategy that does not address the existing situation. We need to act to improve the school environment within and without immediately.

The strategy largely seems to rely on hopes of self-regulation and voluntary initiatives. The food and beverage sectors are keen to have acknowledged that they have made changes, and consider they should be left to decide voluntarily where to draw the line. It is important that the "healthier" label flashed on many products is not simply a way of justifying a price premium when demand for healthy food is soaring. Truly healthy food needs to be mainstreamed. Price incentives should steer consumers towards those healthy choices, which should not be the unaffordable preserve of the better off. If the food industry wants to capitalise on the "healthy" label, it must accept the antithesis - and label the rest of its products transparently. Consumers need to be reassured that claims are valid, and not just clever marketing ploys, so the strategy's proposed "healthy food code of good practice" needs to deliver precisely what it says on the label and not fudge the established World Health Organisation (WHO) expert recommendations on diet.

So far the voluntary approach has only created consumer confusion and a battleground, offering little prospect of a simple resolution. But there is a toughening stance behind the government's strategy that recognises that a robust and universal traffic lights labelling system is essential. This has already paid off for those supermarkets that have tested this approach. The challenge is whether reluctant retail giants - operating not just in the UK but with tens of thousands of food products sold throughout the EU market - are ready to fall in line.

One area where voluntary measures are clearly insufficient is marketing to children. It is encouraging that Ofcom is being urged to review the option of a nine o'clock watershed on junk food advertising, yet the food industry is already braced to challenge Ofcom's restriction on advertising directed towards children up to the age of 16. Even so, it is clear that in the absence of regulation, corporate responsibility does not always extend into the new media where children are vulnerable to sales campaigns that target them online. As the final touches were being put to the government's obesity strategy on Tuesday, the UK was among members of the WHO's executive board in Geneva to support a call for a much stronger global action plan to prevent non-communicable diseases - including measures to combat obesity, a costly driver of type-2 diabetes, heart disease, some cancers and many other health risks.

Among the actions on which WHO was urged to take a more pro-active role are proposals for tax measures and labelling to encourage healthier eating and activity; legislation to require better quality food by cutting down on unhealthy fat, sugar and salt content; and clear recommendations to control marketing to children. These remain key issues that need to be addressed far more vigorously not just in the UK but globally if any obesity strategy is to succeed.