Calorie intake increased by up to 15 per cent in the pandemic as Britons turned to cooking to cope with lockdown stress, according to research by the Institute for Fiscal Studies (IFS).

Nine in 10 households increased their total calories as they were forced to work from home, raising the risk of rising obesity if the trend continued, the IFS said.

The biggest increases were among wealthier middle-class households, while the smallest increases were among the retired, many of whom had to shield and were reluctant to go out and buy food during lockdown, and among poorer families, who struggled financially during the pandemic.

Calories from takeaways doubled from 50 calories per adult per day to 100 in the second national lockdown, but the biggest shift was towards cooking at home using raw ingredients. 

By May 2020, Britons’ calorie intake was 15 per cent, or 370 calories per adult per day, higher than normal, and was still 10 per cent, or 250 calories, above normal on average in the second half of 2020.

The IFS researchers said the combination of the closure of offices, workplaces and restaurants and the shutdown of leisure and sporting venues meant people had significant amounts of time on their hands, which they used for cooking and eating.

This was only reversed for one month in August 2020, when Rishi Sunak, the Chancellor, launched his Eat Out to Help Out scheme.

"A notable feature of dietary responses to the pandemic is a switch in the composition of calories away from ready-to-eat and prepared foods towards raw ingredients," said the researchers.

Yet, despite ostensibly healthier cooking using raw ingredients, the amount consumed has had an impact on the nation’s waistline.

Martin O’Connell, IFS deputy research director and an author of the research, said: "An important question for policymakers is whether higher calorie consumption persists as we emerge from the pandemic. 

"Our findings point towards increased home working as a factor in driving higher calorie consumption. This could exacerbate the challenge of improving population diet and reducing obesity levels."