The finding, based on a unique study of the nation's health and diet which started in the Thirties, offers a possible explanation for the increase in cancer which now affects one in three of the population: that we are getting bigger. Cases of cancer have risen 30 per cent among women and 21 per cent among men between 1979 and 1991 and this is only partly explained by the ageing of the population.
Latest figures published yesterday show that cancer has overtaken heart disease to become Britain's biggest killer. Nearly 9,000 more people died from cancer than from heart disease in 1996, according to the Cancer Research Campaign.
Success in combating heart disease, deaths from which have fallen sharply, has highlighted slower progress in tackling cancer, chiefly because of the difficulty of persuading people not to smoke - especially the young and women.
In another development yesterday, lung-cancer sufferers seeking compensation from tobacco manufacturers scored a significant advance when the High Court lifted gagging orders on the plaintiffs and ruled that they would not be liable for huge legal costs if they lost.
Smoking is the chief cause of cancer and outweighs all other causes. But the study of children's diets, published in the British Medical Journal, shows that the quantity of calories eaten affects the risk of developing cancers other than those related to smoking.
Almost 4,000 children whose diets were closely monitored in the late Thirties were followed up for 60 years. One in 20 had died of cancer and the risk was highest among those who ate most as children. For each extra megajoule - 239 calories - eaten daily, the risk rose 20 per cent for non-smoking-related cancers, allowing for other factors such as income and social class. A megajoule is about a tenth of the average adult daily diet, equivalent to a chocolate bar, a ham sandwich or a piece of cake.
The finding reinforces the message that overeating in childhood carries long-term risks. But researchers from the University of Bristol, who carried out the study, warned that it should not be taken to mean food was bad for health.
Stephen Frankel, professor of public health medicine, who led the research team, said: "At any age the individual risk of getting one of these non- smoking related cancers is small. This research shows there is a relation between energy intake and the risk of cancer and that is important in understanding the causes of cancer."
Tall people are already known to be at greater risk from cancer and average heights - and girths - have been increasing over the past 50 years with improving diet. Obesity has doubled since 1980. Research on animals has shown that restricting calorie intake slows the biological changes associated with cancer and ageing.
Cancer is triggered by a genetic mutation which causes the cells to multiply out of control and children who eat less may be at lower risk because they grow more slowly. Professor Frankel said: "If there is more of you there is more chance of one of these unwelcome mutations occurring. The simple fact that the cells are growing more slowly reduces the chance of genetic changes."
But, he said: "Within each income band, the more you eat the greater the likelihood of cancer. That holds as long as you are eating enough. No one is recommending starvation."Reuse content