Parents of preschoolers are being told to not worry about Body Mass Index test results.

The test uses a person's weight and height to classifying them as underweight, average, overweight or obese.

The test is used by health professionals during the Ministry of Health's Before School Checks.

Registered dietitian Lucy Carey told Kate Hawkesby it tells some children they're fat, when they're not.

She says some All Blacks are classified as obese, because of their muscular physiques.

'A lot of people don't realise how inaccurate the test is."

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