Nearly a third of 11 year olds in Jersey are overweight or obese.
3 in 5 over 45s also fall into those categories.
The latest data of height and weight measurements of children starting and leaving primary school shows 2 in 10 Reception-aged children are overweight or obese.
That rises to 3 in 10 Year 6 pupils, by which time more boys than girls are above a healthy weight.
One in six adults are obese. There has been little improvement in that figure in the past decade.
Only a quarter of 11 year olds get the recommended hour a day of exercise, and only half of adults do at least 2.5 hours a week of physical activity.
Statistics Jersey's Obesity, Diet and Physical Activity Profile includes data from a number of different sources.
It also suggests:
*Two-fifths of 16-34 year olds are classed as overweight (Body Mass Index of 25-30) or obese (BMI 30+), compared to almost three-fifths of people aged over 45.
*Just over a third of adults eat 5 portions of fruit or veg a day.
*46% of boys and 33% of girls in Year 6 spend three hours or more a day on electronic screens. That rises to more than 70% of children in Year 10.