The States Director of Public Health policy is calling for patience in the bid to reduce child obesity in Jersey.
A quarter of boys and 16% of girls in reception are classed as overweight or abuse.
That increases to 1 in 3 pupils by the time they leave primary school.
Martin Knight says more people today are choosing high sugars, salts and fats instead of fresh fruit and vegetables.
He's confident of changing habits, but warns it will take time.
"There's so simple fixes in the short-term. We've been investing through our food and nutrition strategy. It's got a strong focus on addressing dietary behaviours with the youngest in our population recognising that we can improve children's eating habits and take healthy behaviours with them into adulthood.
"Then we'll start to see improvements around nutrition, weight and the reduction of risk for future disease."
Three in ten children who were overweight six years ago have become obese or severely obese.
It was also revealed that more children from urban homes are above a healthy weight than those from rural parishes.
"We haven't seen a change over the last two or three years. I'm not necessarily surprised, these habits have developed and have embedded within the culture of the island. We need to do more to shift that.
"We know that urban areas have high levels of depravation and poverty, they have less green space, there's greater exposure to fast-food outlets and energy-based foods from supermarkets in that geographical area are more easily available.
"These things all impact on our individuals and in families choice around diet and exercise." - Martin Knight - Public Health.
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