Alex Butler - whose height makes him FIVE INCHES above the national average for his age - was examined under the Government's Change 4 Life campaign, and his results were sent home to his mum Karen.
She was outraged to receive a letter which informed her: "You may be surprised your child's result is in the overweight range.
"It can sometimes be difficult to tell if your child is overweight as they may look similar to other children their age.
Research shows that children who are overweight or very overweight have higher risk of ill health during childhood and later life."
Karen, from Ibstock, Leicestershire, was advised to put into place 'lifestyle changes' to reduce Alex's weight. She told The Sun: "I was horrified. Alex is on the go all the time and I make sure he eats healthily.
"He loves running around and cycling, he literally never stops for a second and is always playing in our garden.
"After the letter arrived he said to his dad Kevin, 'I'm not fat, am I daddy'? We told him, 'Of course not, you're absolutely normal'."
Alex was found to have a BMI of 95 - four points over the 'healthy' limit.
His 6ft 5in dad Kevin, 43, said: "Alex is the height of a six or seven-year-old so obviously has a larger frame.
"Not everyone is average height and build. It's not a good measurement and is very misleading because Alex is not overweight."
Leicestershire and Rutland PCT who carried out the test said: "BMI is not a perfect measure but is accepted as one of the best ways to tell if a child is a healthy weight. We write confidentially to parents. It is up to them if they want to share and discuss the results with their child."
Five-year-old branded overweight by NHS
Have you had one of these letters? Were you - or your child - upset by the test results?