Putting calories on food labels and menus "is no silver bullet" say researchers, who analysed the best evidence to date on how effective the policy can be.A review of 25 studies on calorie labelling in a number of countries found a small reduction in the calories people chose to eat - equivalent to two almonds - but even this modest effect could help prevent adults putting on weight as they get older.

Calorie labels in supermarkets and restaurants have little impact on consumer choices, researchers found, fueling doubts about whether the practice is worth keeping.