Filmgoers should be told how many calories there are in the popcorn, ice cream and softdrinks that they buy in cinemas, according to the Food Standard Agency.
Smaller popcorn buckets and drink cups should also be made available, the nutrition inspector said.
Tim Smith, chief executive of the agency, told The Times that cinemas should help to deal with the country's overweight crisis.
"There is a misbelief that popcorn is calorie-free, but that is not the case. It is a concern to us," he said. "Portion sizes are also a big issue, and there seems to be increasingly big packs onsale."
He spoke as a number of food chains such as Pret A Manger, Wimpey and The Real Greek decided to put calorie counts on all their menus.
A trial scheme(试行方案) with 21 food companies took place last summer, and indications are that consumers altered their buying habits when they realised the number of calories in a product.
A consultation(征询意见) on the trial ends next month but Mr Smith is already planning the second drive for American-style calorie counts and is anxious to win support from cinemas and other entertainment places, from football grounds to concert halls.
Government figures suggest that two thirds of adults and a third of children are overweight. If trends are not reversed , this could rise to almost nine in ten adults and two thirds of children by 2050, putting them at serious risk of heart disease, cancer and other diseases.