PEOPLE buy unhealthy food because they like it. It is tasty and filling. It is often full of salt or sugar, or both.
It is also much cheaper than the healthy variety, and the gap is widening. Not only have the prices of fruit and vegetables risen, but the pace has accelerated. The price of potatoes, one of the most nutritious foods, has gone up by 19pc in the past year.
Meanwhile, fast-food prices have remained static or even fallen.
And the ill-effects of this state of affairs are not evenly spread across the population. Typically, poorer people eat less healthy food. The better off will continue to consume fresh fruit and vegetables, their high prices notwithstanding, even if incomes have suffered.
The striking difference in patterns according to income and social class has to be considered when grappling with the statistics which show that we are second only to Britain in the European nations most vulnerable to overweight and obesity.
For decades now, experts have pointed to the shocking example of the United States, where obesity costs $100bn a year, and warned that Ireland too could experience an "obesity epidemic".
In addition to Irish love of junk food, one must take account of Irish dislike of exercise. Most middle-aged and elderly Irishmen take no exercise at all.
It may well be thought that campaigns in favour of healthy eating should be directed at the lower end of the age scale. In fact, Irish sports stars, notably John Treacy, have taken a prominent part in such campaigns.
But that has not prevented the increase of obesity among teenagers and even among children under 10 years old.
Sadly, there is little or no prospect of a reversal in the present adverse pricing trends. Much can be done in the way of labelling and information. But the issue cannot be tackled in any substantial way without direct government intervention. The Department of Health, for all its present woes, must take the lead. It must make the case that fruit and vegetables point the way to the nation's health, and an unwise diet will one day exact a heavy price.
Lara's death highlights need for urgent action
Lara Burns Gibbs from Maynooth has taken her own life at the age of 12. She becomes the third young girl to die by suicide in recent months, following Erin Gallagher (13) from Donegal and Ciara Pugsley (15) from Leitrim.
The "social media" have carried rumours that her death, like those of Erin and Ciara, was caused by cyber-bullying, but the Garda Siochana say they have received no complaints of this kind.
Careless assumptions will not help to alleviate the difficult and painful problem of youth suicide. The correct approach was well illustrated by Johnny Nevin, principal of Lara's school. He said that the school had implemented its own critical incident management plan and its guidance team was working with the National Educational Psychological Service.
Of course that addresses only one side of the question. There is now an urgent need to tackle the issue of prevention.
Education Minister Ruairi Quinn is expected to produce a national action plan on bullying shortly. But bullying is only one of many actual and possible causes of suicide. They include domestic violence and substance abuse.
In the case of those in their early teens or about to enter adolescence, the first place in which problems should be identified is the home; the next, the school. There, they must be helped through the traumas of the most sensitive moment of their lives.