A new study has revealed that exercise may not be effective in preventing childhood obesity.
Experts believe that children are programmed to be sporty or sedentary and pushing them into exercise may have little effect on whether they are fat or not.
The study showed that even though fewer than half of boys and only one in eight of girls do the recommended one-hour's activity per day this is not reflected in their weight.
The research involving almost 300 five years old school children in Plymouth found that the amount of exercise a child does is not correlate with their Body Mass Index.
Those who did more physical activity were healthier when they measured the fat levels in their blood and blood pressure but the amount of activity they did not impact the fat.
"Each child is programmed to a particular level of activity whatever you do to them they will modify their activity to remain at that level, some will always do more and some will always do less," Telegraph quoted Co-author Prof Terry Wilkin.
"Some children do meet the physical activity guidelines and some don't but BMI will not tell you which ones do and which ones don't. But it is worth doing exercise because there is clearly a benefit in doing so, it is just that the BMI does not reflect that.
"We are getting away from the notion that we are a nation of couch potatoes and that is why we are fat, it may well be more to do with diet as that has markedly changed over time," Wilkin added.
During the study, the researchers examined the physical activity levels of the participants at the age of five, six, seven and eight with the help of a device put around their waist.
The research paper concluded, "In children, physical activity above the government-recommended intensity is associated with a progressive improvement in metabolic health but not with a change in BMI or fatness."