Thousands of people die each year from illnesses linked to fuel poverty, according to an independent report.
Professor John Hills has called for a new definition of the problem, which focuses on people with low incomes driven into poverty by high fuel bills.
His report found that in 2004, fuel-poor households faced a shortfall of £256 to heat their homes and avoid poverty, but in 2009 it was £402.
Recent bill increases may make the problem worse this year, he warned.
The government commissioned Prof Hills, director of the Centre for Analysis of Social Exclusion at the London School of Economics, to examine how serious a problem fuel poverty is and how it should be measured.
He argues that fuel poverty poses serious public health and environmental issues.
His report is the first to measure the shortfall that some households face in heating their homes, which he calls the fuel poverty gap.
Further increases in bills since then are likely to have widened this gap, he warned.
The report argued this shortfall had serious implications for health.
There are 27,000 extra deaths in the UK each winter compared to other times of year, according to figures from the Office for National Statistics. The report found most of this was due to cold weather.
That figure is one of the highest in Europe and worse than Finland, the Netherlands, Germany, Sweden, Norway and France.
The main cause of these deaths is respiratory and cardiovascular illness brought on by the cold, with lower outdoor and indoor temperatures each accounting for about half the total number of deaths.
Prof Hills then drew on a separate recent report, the Marmot review, which found that more than one-fifth of all additional winter deaths were directly attributable to lower indoor temperatures in homes that, on average, are among the coldest 25% in the country.
Not all of these deaths could be directly attributable to fuel poverty as some homes may be cold for other reasons, so Prof Hills and his team estimated that around half of those deaths were for economic reasons.
This meant, the Hills report concluded, that an estimated 2,700 people die each year because of health conditions, such as respiratory infections or cardiovascular problems, linked to fuel poverty.
"It's a very serious problem," said Prof Hills. "There are people dying, maybe more people dying each year than die on the roads, it's a problem of hardship for low-income families who are having to pay out more when they've got hard-to-heat houses and it's a problem for countering climate change."
Low-income households are unable to invest in energy efficiency measures, hindering efforts both to reduce their bills and to lower UK carbon emissions.
However, Prof Hills found that the way we define fuel poverty may need to change.
By the old definition, a household was defined as being in fuel poverty if 10% of its income was spent on fuel each year.
The latest figures from the Department of Energy and Climate change suggested four million English households fitted into this category in 2009, in a sharp increase from 1.2 million in 2003.
Estimates from the Centre for Sustainable Energy suggest that number has risen to 5.5 million for England and an estimate of 6.6 million for the UK.
But Prof Hills suggests the current definition did not focus tightly enough on fuel poverty.
Instead, he suggested people be defined as fuel-poor only if their bills were relatively high and if paying those bills would push them below the poverty line.
That would mean that in 2009, fewer people were classed as fuel-poor - 2.7 million in England.
However, the problem appears less variable, with roughly the same number categorised as fuel-poor in 2003, more than double the estimate for that period on the current definition.
The government says it is already taking measures to tackle the issue.
It has recently announced the Warm Homes Discount on energy bills, which includes reductions of about £120 to the poorest pensioners in addition to winter fuel payments.
Energy suppliers are also obliged to offer free or reduced packages on home insulation to some high-risk groups, using money recouped from a charge on energy bills.
However, some government measures, such as the Warm Front Scheme designed to help insulate low-income homes, are due to end next year.
Derek Lickorish, chair of the Government's Fuel Poverty Advisory Group (FPAG), called the figures for the number of deaths due to fuel poverty a "disgrace".
"Insulating the homes of the fuel poor is the only long-term and sustainable solution to solving this problem, but they will need financial help to make this happen and this takes time. Urgent action must start today," he said.
Some charities have initially welcomed the report.
Citizens Advice provides advice to families struggling to pay their bills.
"It's horrifying that so many people are dying each year because they can't afford to heat their home," said Citizens Advice chief executive Gillian Guy.