One in five households said their monthly incomes would not stretch to cover all of their food costs in April and they had to use some form of borrowing such as a credit card, overdraft or loan or plunder their savings instead, consumer group Which? found.
This would equate to five million families if the findings were projected across the UK, Which? said.
The findings provide an indication of the numbers of people who are struggling, despite official figures showing last week that personal insolvencies have fallen to their lowest level in five years.
The group who could not cover their food bills from their income alone was largely made up of low-income households earning less than £21,000 a year and squeezed 30 to 49-year-olds, many of whom had children.
Some 82 per cent of these people said they were worried about food prices and 57 per cent were finding it “difficult to cope” on their current income.
People in this group were also more likely to be worried about their level of debt and 74 per cent of them described the economy as “poor”.
Which? executive director Richard Lloyd said: “Our tracker shows that many households are stretched to their financial breaking point, with rising food prices one of the top worries for squeezed consumers.
“It’s simply shocking that so many people need to use savings or credit to pay for essentials like food.”
The study also found that only one quarter of people said they were living comfortably on their incomes and more than one third (36 per cent) felt squeezed.
Two-thirds are worried about the effects of low interest rates on their savings – although insolvency experts have credited low interest rates with helping people’s borrowing costs and keeping personal insolvencies down.
Almost one third (31 per cent) people surveyed cut their spending on essentials last month, and they were most likely to be women aged between 30 and 49.
Over two thirds (68 per cent) of people across the survey described the state of the economy as poor, although nine per cent said it was good.
Around 2,000 people took part in the survey last month across the UK.
The results of the survey come days after South Yorkshire Police revealed a sharp rise in shoplifting cases where thieves were targeting foodstuffs in the Rotherham area, indicating that a black market in cheap stolen food may be starting to appear.
One of the offenders dealt with by police and the courts had stolen food and alcohol worth more than £3,700 from the same branch of Morrisions in Rotherham.
The trend has prompted police to issue a warning that they will pursue shoplifters while consumers are being urged to guard against buying goods they know to be, or suspect to be, stolen because by doing so they are also committing a crime.
Police believe some criminals may be trying to tap into a market of those willing to buy suspect foodstuff as an easy way to finance their own lifestyle.
There has also been an increase in the use of food banks in the region, where food donated by individuals or companies is redistributed among those who are unable to feed their families.
Recipients are normally referred to such schemes and the latest to open in this region is in Worksop, north Nottinghamshire.