The cost of eating a healthy diet is becoming increasingly unaffordable for a large swathe of UK families, new data from The Food Foundation shows.

Comparing the cost of the government’s recommended Eatwell Guide with data on household expenditure and disposable income, the foundation found that the bottom 20% of UK families (earning less than £15,860 a year) would need to spend 42% of their disposable income after housing costs to afford the healthy diet recommendations.

In the UK, 3.7 million children live in these low income households, and are likely to be unable to afford a healthy diet as defined by the government, the foundation said.

The results highlighted an urgent need to ensure the incomes and resources of low-income households were adequate for purchasing a healthy diet, and to take measures to support these households in affording the foods contained within the Eatwell Guide, it added.

Widening inequality was also leading to higher rates of childhood obesity in deprived areas with 26% of children in Year 6 being obese compared to 11% in England’s richest communities, the report said.

“The government’s measurement of household income highlights the fact that millions of families in the UK cannot afford to eat in line with the government’s own dietary guidance,” Anna Taylor, executive director of the Food Foundation, said.

“It’s crucial that a coordinated cross-government effort develops policy that accounts for the cost of its recommended diet, and creates a food system that does not consign those on lower incomes to the risk of diet-related illness.”

The report comes as the Children’s Future Food Inquiry continues to gather evidence on children’s food insecurity in the UK.

The parliamentary inquiry is joining calls for a national measurement for food insecurity, and next year will present recommendations to policy makers for understanding and tackling children’s food insecurity and its consequences in the UK. 

The Eatwell Guide splits the diet into a five category pie chart: fruit and vegetables; potatoes,bread, rice, pasta and other starchy carbohydrates; beans, pulses, fish, eggs, meat and other proteins; dairy and alternatives; and oils and spreads. Each section of the pie chart is based on the proportion of the diet that should come from each category.