The FSA wants smaller portions to be available at cinemas
Movie-goers should have more information about how many calories are in cinema snacks, the Food Standards Agency (FSA) said.
The nutrition watchdog is concerned about the portion sizes of cinema snacks which are often high in fat, sugar or salt.
The FSA said that cinemas sell "pretty large portions" and do not offer a smaller choice to customers.
FSA chief executive Tim Smith told The Times cinema food was "a concern".
Mr Smith said there seemed to be increasingly large snacks on sale. "Who would ever have thought of the idea of a family needing a wheelbarrow to go into a cinema?" he said.
"There is a myth that popcorn is calorie-free but that is not the case."
A spokesman for the FSA also said the watchdog did recognise how trips to the cinema were "occasional treats" for people, and that food eaten there "only represents a small amount of the nation's calories".
"However, the food on offer at cinemas is food that is often high in fat, sugar and salt," they said.
"It is also served in pretty large portions and people don't have a choice to choose something smaller, for example the smallest soft drink on offer can be as big as a pint and popcorn tends to come in large buckets.
"The FSA thinks it's a good idea that people should have more choice. If they want to order a smaller popcorn box or soft drink then it should be available."
The FSA is currently consulting on a calorie labelling scheme for some food businesses and will publish its final recommendations in the summer.
The Times said a large sweet popcorn from a central London cinema weighed 375g (13oz) and was likely to contain around 1,800 calories.