Poor diets cost the NHS £6bn a year in ill-health - three times as much as smoking, a study suggests.
Poor diets can cause heart disease, cancer and diabetes
Researchers calculated the figure by studying the death rates and prevalence of food-related problems such as heart disease and cancer.
The British Heart Foundation team said the figure, which includes treatment, prevention and care, showed more had to be done to combat unhealthy eating.
The study was published in the Journal of Epidemiology and Community Health.
Research has shown that bad diet can cause heart disease, cancer, tooth decay and diabetes.
The cost of treating people in the UK who develop these totals £18bn.
But the researchers acknowledged that not all cases of these diseases were caused by diet.
Instead, using previous research by the World Health Organization, government and independent scientists, the researchers calculated that about a third of this could be attributed to food.
The team admitted the figure was crude, but said it could still be used to help form policy.
Report co-author Mike Rayner said: "The estimates suggest that the burden of food-related ill-health is large with, say, smoking, and suggest that food-related ill-health has been neglected by heath and food policy-makers.
"For example, while there are specific government targets for smoking in England there are no equivalent dietary requirements."
He called for the government to introduce food labelling and restrictions on TV advertising to help change dietary habits.
Anna Denny, nutrition scientist at the British Nutrition Foundation, said while it was a "crude" estimate, the study highlighted the growing burden of ill health attributed to food.
"Today, more adults are obese than ever before and the World Health Organization estimates that dietary factors account for 30% of cancers in industrialized countries.
"It is important to get clear messages across to consumers regarding diet, and to make it as easy as possible for consumers to choose a healthy balanced diet."
But Professor John Appleby, chief economist at the King's Fund health think-tank, said in reality it may be cheaper not to intervene as the costs of the health care can be less than the cost of changing lifestyles.
"The most cost-effective action is to get GPs to tell people to change their lifestyle, but that does not work.
"What you need in reality is some pretty major interventions, perhaps interfering with the food market through advertising bans, and on top of that these measures take a long-time to have an impact."
And a Department of Health spokeswoman said: "We are well aware of the links between poor diet and ill health including heart disease, cancer, diabetes and stroke."
And she added the government was taking a range of measures to combat unhealthy eating.
She pointed out warnings had been issued over salt intake and consultation was ongoing on food labelling and restrictions on junk food advertising to children.