Soaring obesity levels are being exacerbated by a fifth of households struggling to get hold of good quality food at reasonable prices, a cross-party group of MPs has warned.

The Environment, Food and Rural Affairs Committee told ministers they must break the “junk food cycle” as high food insecurity will contribute to a forecasted 40 million UK adults being obese in little over a decade.

Their report published on Friday said nearly 18% of households experienced moderate or severe food insecurity in January as prices hit 40-year highs.

Ministers were urged to consider extending free school meal eligibility as 800,000 children – a third of those living in poverty – are estimated not to be entitled to the provision amid evidence the substantial benefits could outweigh the costs.

The MPs also raised concerns that “many households are skipping meals” as supermarkets pay high levels of dividends to shareholders.

The NHS will be hit by “very significant costs” owing to a forecast that obesity rates are expected to rise by a further third to around 40% of adults in 2035.

Sir Robert Goodwill, the Tory MP who chairs the committee, urged the Government to “read the report carefully and act accordingly”.

“Food security matters to us all. It is vital to farmers; it is vital to other food producers. And of course, it is vital for every citizen up and down the land to have a square meal at a reasonable price,” he said.

“But surprisingly, the Government does not appear to be taking this very basic matter anywhere near seriously enough.

“This report is calling, through its various recommendations, for much more attention to be paid to the guaranteed supply of good quality food – at prices which suit both producers and consumers. I know that is not an easy balance to strike. But that’s what government is for.”

The MPs warned that food that is high in fat, sugar and salt is “often considerable cheaper” per calorie than healthy food, fuelling obesity levels in poorer households.

They urged the Government to support people to make better choices more accessible and affordable as part of an obesity strategy.

Ministers were urged to carry out a full impact assessment of the introduction of a sugar and salt tax that could help drive healthier choices.

A Government spokesman responded: “We know food prices are worrying for households across the country, which is why we’re sticking to our plan to halve inflation this year, and ministers are keeping in close discussion with the industry about the cost of food.

“We have introduced a number of measures to tackle obesity, recently implementing clear food labelling guidelines to help people make healthier choices for themselves and their family when eating out or getting a takeaway. We estimate there will be a reduction of 70,000 children and 300,000 adults living with obesity as a result of this policy.”