Many children risk developing serious health problems because they do not exercise enough.
A new study by the British Heart Foundation and Oxford University found that three in 10 children are already overweight or obese, which could lead to problems such as heart disease later in life.
One in four children between the ages of two and 15 are inactive for at least six hours on each day of the weekend, the researchers found, with the problem found to be worse among teenagers than younger children.
While only one in five 11-year-old girls and one in three 11-year-old boys fail to do the recommended one hour of physical activity per day, the figure soars to 85% of 13-year-old girls and 73% of 13-year-old boys.
The proportion of children watching at least two hours of TV every day was also found to be higher among 13-year-olds than 11-year-olds, with the figure rising from 60% to 68% for girls and from 64% to 74% for boys.
Researchers also looked at children's eating and drinking habits and found that 32% of 11-year-old girls and 38% of 11-year-old boys have a soft drink every day, compared with 39% of girls and 43% of boys in the 13 and 15-year-old age group.
Four in five children between the ages of five and 15 eat fewer than five portions of fruit and vegetables a day, with the figure rising to 83% among 15-year-olds.
Around three in 10 girls and one in four boys aged 11 do not have breakfast, compared with more than a third of girls and nearly half of boys aged 13, and nearly six in 10 girls and four in 10 boys aged 15.
Copyright Press Association 2013