A group of influential doctors and medical experts has called for governments globally to take tougher action in the battle against obesity levels.

In a four-part series of articles on obesity, published in the medical journal Lancet, the group calls for a number of measures - such as taxing junk food, regulating the marketing of unhealthy foods, increased traffic light labelling and school-based education programmes.

In its assessment of the future of the obesity pandemic, the group predicts that, if nothing is done to tackle the problem, more than 40 per cent of people in the UK and 50 per cent of people in the US will be obese by 2030.

The group calls for an integrated action plan involving a wide range of government departments - from health to non-health sectors such as trade, agriculture, transport, urban planning, and development.

It added that no government had yet been successful in facing up to the rising levels of obesity.

Dave Stalker, chief executive of the Fitness Industry Association, welcomed the call for a united front to tackle the issue.

He said: "The Lancet article serves once again to remind us that the public health challenges we face waits for no man; it just gets progressively more of a challenge as each year goes by.

“Government has to act in a concerted fashion, at a scale reflective of the problem and enlist the support of the private, public and third sector in making a change in the way we live as a nation.

“Getting more people, more active, more often is still as crucial as it has always been (especially given the wider benefits to health other than weight management), but we need to recognise that at a population level, removing calories from the national diet or improving the quality of what we eat, is just as important."