Watching one episode of Britain's Got Talent could cause children to eat an additional 50 calories, a study has found.

The Obesity Health Alliance analysed adverts during six live episodes of Britain's Got Talent over one week in May and June, finding that 23 per cent were for food or drink high in fat, sugar and salt such as pizza, burgers and ice cream.

According to the OHA, a child who watched all six episodes in one week would have seen more than 22 minutes of unhealthy food and drink adverts, which the charity calculated could lead to them eating an extra 300 calories.

Recent research found that seeing 4.4 minutes of food advertising was associated with children eating 60 more calories a day, while eating as little as 46 extra calories each day could lead to excess weight.

Britain's Got Talent is regularly watched by hundreds of thousands of children, viewer figures show, but is not classed as "of particular appeal" to children under current rules, meaning restrictions on junk food advertising do not apply.