The average Briton consumes 50 per cent more calories than they realise, according to the first estimates from the Office for National Statistics.
The new data show that men are the worst at kidding themselves – typically consuming 1,000 more calories than they estimate every day – while women eat about 800 calories more than they account for.
And the more people eat, the less reliable their estimates are, the research found.
Experts said the delusion occurs because people do not like to “be taken for slobs” – and ended up lying to themselves.
The revelation comes as Public Health England (PHE) prepares to launch a calorie counting campaign, as part of efforts to combat Britain’s obesity epidemic.