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Predicting a child's weight or obesity

Mother and children picking vegetables
Credit: iStock.com/RyanJLane

Until recently, parents with concerns that their young children are overweight haven’t had access to any easy answers. Is intervention really necessary? Will they simply grow out of it?

A new study led by Melbourne’s Murdoch Children’s Research Institute and published in the International Journal of Obesity, has found experts now know how to reliably determine if the child in front of them will regain a healthy weight over time.

“We were trying to address a clinical question that GPs, paediatricians, dieticians and maternal health nurses all face. That is, when children come to see them they don’t have the tools in front of them to know which children will go on to enter a heavier weight range.

Equally, they don’t know which of the heavier children will naturally return to a healthier weight,” says Dr Kate Lycett, an Honorary Fellow with the Murdoch Children’s Research Institute and a Research Fellow at Deakin University’s Centre for Social & Early Emotional Development.

Asking the right questions

By sourcing data from a large population-based study which measured participants health and weight every two years for a decade (the Longitudinal Study of Australian Children), researchers were able to determine that of all the measures or questions that a clinician could assess, just three factors could predict the onset or resolution of weight problems by adolescence, particularly from children aged 6-7 years or older.

The three factors are: a child’s and mother’s Body Mass Index (BMI) and the mother’s education level.

“One of the surprising things was that questions about fatty foods and whether children enjoyed physical activity weren’t the strongest predictors, although of course we know that diet and physical activity are so important for overweight and obesity,” says Dr Lycett.

She believes the objectivity of a measure like BMI is important, as it doesn’t rely on a patient’s recall about what they’ve eaten or how much they’ve exercised.

“It’s very challenging for children or parents to respond to questions like that in a short clinician session. Measuring things like height and weight are more objective,” says Dr Lycett.

On the other hand, the connection between BMI and a mother’s education level was expected.

“We know that a lot of chronic health conditions have what we call a ‘social gradient’, and that more disadvantaged groups are more likely to be overweight or obese,” says Dr Lycett.

“The Australian Institute of Health and Welfare’s latest report shows that and we see it all around the world. It really brings home the message that we need to address inequity.”

One of the surprising things was that questions about fatty foods and whether children enjoyed physical activity weren’t the strongest predictors, although of course we know that diet and physical activity are so important for overweight and obesity.
Dr Kate Lycett

How the connection impacts childhood obesity

Researchers found that if all three risk factors are present, children who are overweight or obese early in life have a low chance of resolving their weight problems by adolescence. In fact, the prevalence of being overweight/obese at the age of 14-15 years was 71 per cent among those with all risk factors.

In comparison, the risk of being overweight or obese at the age of 14-15 years was 13 per cent among children with none of these three risk factors at age 6-7 years.

Dr Lycett said identifying these three factors may help clinicians predict which children will develop and resolve excess weight with about 70 per cent accuracy.

“Nothing will give us one hundred per cent accuracy, but this gives us a useful tool; prior to this we haven’t had anything,” Dr Lycett says, noting that until now most studies have overlooked the important questions around which children are likely to become overweight/obese.

These quick and easy predictors are particularly useful given that most parents don’t bring their child to a health professional due to weight issues.

“Children come into an appointment for something like allergy, asthma or mental health: it’s very rare they come about being overweight. There’s such a small window of time [in an appointment], so the questions need to be short and things clinicians can ask or readily measure on the spot,” she says.

While Dr Lycett acknowledges exploring weight issues with young child is challenging, she emphasises its importance.

“We know it’s really hard, because overweight and obesity are really complex issues. But it’s really important that children get checked because there are other outcomes that are linked to obesity: quality of life issues or other problems children may be experiencing like anxiety or, in their teenage years, high blood pressure. Clinicians can address those,” says Dr Lycett.

The importance of timing

Five years ago Dr Lycett and her colleagues published a paper in the academic journal Pediatrics which shows that for a large number of children, their weight issues do naturally resolve.

This is important for a number of reasons:

“It’s obviously a hard issue to raise with families, plus, we don’t want clinicians to be spending time on interventions if it’s not necessary,” says Dr Lycett.

For those who do require intervention, timing is important. This isn’t simply because researchers know that children who are overweight or obese are more likely to experience the same issues in adulthood.

Dr Lycett explains that her Finnish colleague, Professor Markus Juonala, has discovered that what happens with our weight in childhood has “a lot of power”.

“We have shown that for children who are overweight, if we can reverse it by young adulthood they will end up with a similar metabolic profile as children who had never been overweight or obese,” she says.

“There’s great evidence for this, and it’s why we say childhood is a great time to intervene. If we can shift these behaviours early we have more likelihood of reversing obesity across society.”