The number of obese children in England has risen in the last eight years, especially in kids aged eight to 10.
Between 1995 and 2003 the number of kids in the UK who are overweight enough to harm their health jumped from 9.9% to 13.7%.
The government figures also show kids are more likely to be overweight if their parents are as well.
London has the highest number of overweight and obese children, while Yorkshire and Humber have the lowest.
The study also found that the percentage of obese kids is higher in areas where poorer families live.
The people who wrote the report said they're worried about overweight and obese children because they're more likely to stay too heavy as adults.
That can mean serious problems for their health, as obesity can be a factor which leads to diabetes and heart disease.