It is clear that trying to persuade or "nudge" people into healthy behaviours has not worked and that we need more serious public-health measures to address obesity and other illnesses.

The most successful approaches have been those backed by legislation, such as seatbelts and the bans on tobacco advertising and smoking in public places. No government has yet been brave enough to legislate in the field of obesity – recently the focus has been to form partnerships with industry and food manufacturers.

These partnerships have not led to successful self-regulation or a more healthy food environment, and it is difficult to see how continuing this approach will work.

Obesity has risen inexorably for the past 30 years, despite attempts by successive governments to persuade people to eat healthily, be active and maintain a healthy weight.

The legacy for our children is stark. More of them than ever are developing Type II diabetes, a condition once only known in adults, and whole generations will die before their parents as a result of obesity-related disease. One report estimated that by 2020 one-third of adults, one-fifth of boys and one-third of girls would be obese.

There is so much that could be done with a mixture of legislation, taxation and regulation. We could use the funds raised by taxes on unhealthy foods to subsidise the provision of healthier foods to those on low incomes.

Next week the Royal College of Physicians will launch new guidelines on the treatment of obesity – guidelines which are sadly going to be increasingly needed unless society and the Government grasps the severity of the problem and acts soon.

The writer is a consultant physician with a special interest in obesity and nutrition issues at St George's, University of London