Researchers at Oxford University say that charging Value Added Tax (VAT) at 17,5 percent on foods deemed to be unhealthy would cut consumer demand and reduce the number of heart attacks and strokes.
The purchase tax is already levied on a small number of products such as potato crisps, ice cream, confectionery and chocolate biscuits, but most food is exempt. The move could save an estimated 3,200 lives in Britain each year, according to the study in the Journal of Epidemiology and Community Health.
"A well-designed and carefully-targeted fat tax could be a useful tool for reducing the burden of food-related disease," the study concluded.
The team from Oxford's Department of Public Health said higher taxes have already been imposed on cigarettes and alcohol to encourage healthy living. They used a mathematical formula to estimate the effect of higher prices on the demand for foods such as pastries, cakes, cheese and butter.
However, they said their research only gave a rough guide to the number of lives that could be saved and said more work was needed to get an exact picture of how taxes could improve public health.
Any "fat tax" might be seen as an attack on personal freedom and would weigh more heavily on poorer families, the study warned.
A food tax would raise average weekly household bills by 4,6 per person. Former Prime Minister Tony Blair has previously rejected the idea as an example of the "nanny state" that might push people away from healthy food.
The Food and Drink Federation has called the proposed tax patronising and says it would hit low-income families hardest
It suggests that people eat a balanced diet. The British Heart Foundation said it does not support the tax.
"We believe the government should focus on ensuring healthy foods are financially and geographically accessible to everyone," it said.