The calorie content of popular main meals served in UK and international restaurant chains is excessive and only a minority meet public health recommendations, find two studies in the Christmas issue of The BMJ.
Dining out is becoming more common in many countries, and some studies suggest that people who eat out more frequently are at increased risk of weight gain and obesity.
England's national public health agency recently recommended that midday and evening meals contain no more than 600 calories (kcal) each. But while the poor nutritional content of 'fast food' has been well studied, the energy content of traditional 'full service' restaurants has received less attention.
To better understand the extent to which restaurants are contributing to overconsumption, researchers compared the calorie content of popular meals from major fast food and full service restaurant chains across several countries.
In the first study, researchers at the University of Liverpool analysed the calories in 13,500 main meals from 27 large UK restaurant chains (21 full-service, 6 fast-food).
They found an average of 751 kcal in main meal dishes served by fast food chains, and 1033 kcal in dishes served by full service restaurant chains.
Only a small minority of meals met the 600 kcal public health recommendations, with 89% of full service dishes and 83% of fast food dishes over this limit.
In the second study, an international research team led by researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston, measured calories in the most frequently ordered meals in 116 full service and fast food restaurants across five countries (Brazil, China, Finland, Ghana and India) and compared them with calories in popular US restaurant meals.
They found an average of 809 kcal in main meal dishes served by fast food chains, and 1317 kcal in dishes served by full service restaurant chains. Only restaurants in China served meals containing significantly less calories than US restaurants.
Again, only a small minority of meals met the 600 kcal public health recommendations, with 94% of full service dishes and 72% of fast food dishes over this limit.
These are observational studies, so no firm conclusions can be drawn about cause and effect, and both research groups point to some limitations that may have affected the results.
Nevertheless, they say their findings probably underestimate the number of calories consumed in restaurants because they didn't include drinks, starters, desserts or side orders in their analyses.
The very high energy content of both full service and fast food restaurant meals is a widespread phenomenon that is probably contributing to the global obesity epidemic and is a valid public health intervention target, they conclude.
Potential interventions might be the restaurant industry reducing the number of calories in meals, offering smaller portion sizes for a proportionally reduced price in addition to regular full-size portions, and/or government introducing mandatory labelling of all food products sold by major chain restaurants.
In a linked editorial, Jean Adams at the Centre for Diet & Activity Research, University of Cambridge suggests it might also be important to think further about how different types of interventions work together. For example, combining interventions that target both individual behaviour and local food environments, may have synergistic effects.
If the public health community really wants to effect change, "they need to find ways to transcend ideological debates, appeal to all sides, and acknowledge the potential value of many different approaches," she concludes.