British males who live on beer and fast food - around a third of all men between 16 and 64 - are prime targets for a new government health promotion.

Analysis, funded by the Department of Health, of the diets of more than 2,000 men and women confirm that few young men breakfast on cereals, eat fish or shellfish, consume low-fat dairy products or drink fruit juice or wines. It is time such groups were helped to make healthier choices, suggests the team headed by Jane Pryer, of University College London.

"Factors such as convenience, cost, peer group pressure and occupation may be relevant to food choices and lifestyle," she said.

Most men in what the researchers called the "beer and convenience" category were under 30 and single. "They eat a lot of fat and lack vitamins and minerals. Once you settle on a diet like this it can be a lifelong habit. Our recommended strategy would be to target health promotion at particular diet groups, rather than the whole population."

The latest findings, published in the Journal of Epidemiology and Community Health, will come as a disappointment to nutritionists, even if they help explain why Britain has such high heart disease rates.

Most people studied by the researchers fell into one of four distinct diet "clusters" which differed between the sexes. Less healthy diets were found mainly in the north of England and Scotland whereas those with healthier diets tended to live in southern, central and south-west England.

The beer and convenience category accounted for 34% of men's diets. A further 18% ate the "traditional British diet" with high intakes of white bread, butter, tea, sugar and confectionery. A similar percentage (17.5%) ate plenty of fish, shellfish, fruit and nuts, and drank wine or spirits as part of a "mixed, sweet diet", which also involved a lot of cakes and pastries. A further 17% had a healthier diet involving pasta, rice and coffee.

Among women, 32% ate plenty of white bread, butter and high fat dairy products, but had low alcohol intakes. Neatly 25% ate a "healthier cosmopolitan diet" with high consumption of whole grain cereals, low fat dairy products, fish and wine, low intakes of chips and no beer or cider.