Whose fault is obesity, mum’s or dad’s?


Professor Melissa Wake

1 May 2009

A study reported widely here and overseas discovered that a father’s parenting influences a child’s likelihood of becoming obese, but a mother’s parenting doesn’t.

Using data from the major Longitudinal Study of Australian Children (Growing up in Australia), Professor Melissa Wake and her team created the first snapshot of how a child’s activity patterns, diet, parental characteristics, household income and other factors can influence their weight.

Here she tells Dr Andi Horvath about how they carried out their study and a few of the issues it raised.

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Transcript of podcast

Voice-over: Welcome to this special National Health and Medical Research Council podcast on Ten of the Best Research Projects for 2008. Our pod casts aim to keep you in touch with major health and medical research issues and the people who shape them.

Introduction: Hi, I’m Dr Andi Horvath and I’m at the Centre for Community Child Health at the Royal Childrens Hospital in Melbourne. We’re about to meet Professor Melissa Wake the Chief Investigator of an NHandMRC project entitled, ‘Obesity, Closing the Gaps for a Healthy Family Life.’ The project aims to study the activity patterns and the health of four year olds.

Interviewer: Professor Melissa Wake congratulations to you and your research team. Take us back in time. What was the premise of your investigation, what didn’t we know?

Prof Wake: Well about ten years ago it became evident that we were in the grip, are in the grip, of an overweight and obesity epidemic. We know a lot about adults, we know a lot about older school children – so primary school and teen children – but if we think the genesis of overweight and obesity may be even younger in life we had very, very little information about pre-school children because they’re quite hard to access. ‘The Longitudinal Study of Australian Children’ has a fantastic sample of nearly five thousand pre-school children so we’re able to draw on that sample to look at a whole lot of questions that really weren’t known about pre-school children.

Interviewer: Okay, so how did you formulate your research investigations and what parameters did you use to study these pre-schoolers?

Prof Wake: First up we wanted to know just about the prevalence of overweight and obesity in these pre-school kids and we could do that because this was a national study, then we wanted to know more about things that might cause this problem perhaps and possibly also the effects of it. So we wanted to know: are these children happy, are they healthy as their parents see them, what are their physical activity patterns like, what’s their sleep like, what’s their nutrition like, all those sorts of things which had not been studied in a national sample of Australian children before.

Interviewer: So this was really quite ground breaking.This is information that we didn’t have before, so tell us about the outcomes of your research project.

Prof Wake: Well there were some interesting outcomes although perhaps in the opposite direction to what you might think. First up we found that overweight and obesity are very common even by age four and subsequent data have shown that it’s very common even by age three in fact, so we found that over twenty percent of children were overweight or obese, huge, huge proportion. However, we also found that their parents generally saw them as healthy, there was no difference in the way mothers and fathers reported on the health of their children or their emotional wellbeing or really any other aspect of their health according to them being overweight or obese and that was really new because we tend to think of obese children as being sad, depressed, you know sick, all these things and they’re just not. Parents have far bigger concerns in this age group: they’re concerned about friendships, they’re concerned about readiness for school, they’re concerned about behavior problems. Overweight and obesity by and large in the community, it’s not a big deal for parents.

Interviewer: So it seems that obesity was a little bit invisible to some parents. What can we do about it?

Prof Wake: No I wouldn’t say invisible. Many parents do notice that their children are heavier than other children and many of those parents are concerned about it. I think however, many parents are more concerned about very ‘skinny mini’ little kids in this age group, so it’s not overall that they don’t notice it or that they’re not concerned about it, it’s that for now they have more pressing concerns about their kids which tend to be to do with those social and school readiness and actual physical sickness, so things like asthma, things that make the kids really sick, at this stage. Obesity is something that’s going to make their kids sick many, many years in the future and that’s important to parents in the same way as immunizing their children is important to parents, but it’s not the most pressing issue for them to deal with.

Interviewer: So what does this imply? Is this a problem?

Prof Wake: It’s certainly a problem that we have so many children who are overweight and obese because we know that in a sense this is a time bomb for the adults that they will become, there’s really no doubt about that. In terms of our response I think we need a whole-of-society response, there’s just no doubt about that. We need to make it easier for families to make the right choices as opposed to harder for them to make the right choices and we need to remember that families don’t choose to become overweight. They make their choices on an everyday basis about how they want to live and those choices may then lead on to weight issues.

Interviewer: Because overweight children aren’t necessarily sick children are they?

Prof Wake: In these preschool children, no they certainly weren’t. They weren’t depressed, they weren’t having social difficulties, they weren’t naughty, they didn’t have more asthma, they didn’t have more sleep problems. Generally they were seen by their parents as being indistinguishable and I do just want to say as well that the ‘Longitudinal Study of Australian Children’ is wonderful in this regard because it’s not a study about obesity. The results are very unbiased.

Interviewer: Professor Melissa Wake if you could sum up why you do this research in one or two sentences what would you say?

Prof Wake: Well firstly I love research. Secondly I love the opportunities that are in studies like the ‘Longitudinal Study of Australian Children’ which are just so wealthy in terms of what they can tell us. Thirdly what I research is really common conditions; they’re not rare very serious conditions like cancer or holes in the heart it’s about the common things that really affect all our children. There wouldn’t be families in Australia who aren’t affected by some of the issues that we look at.

Interviewer: This is a huge research project but tell us about your expertise Melissa. Where did you start off?

Prof Wake: Well I’m a paediatrician by training. I trained in New Zealand and originally I was going to be a developmental behavioral paediatrician and I came to Melbourne to do a final year of clinical training and then I guess I was talked in to doing a year of research and I just found that I really enjoyed it and I seemed to have an aptitude for it I guess and I think a lot of people keep going with what they find they have an aptitude with, which might be quite surprising to them as well as to others.

Interviewer: Introduce us to the rest of the team members too because this is a huge study. What sort of skills did you need to bring into this as a Chief Investigator?

Prof Wake: We needed a fantastic statistician so Professor John Carmen fills that bill. Professor Michael Bedman is the time use king of Australia so he has time use diary data going back to the mid 1980s, may be even the 1970s I think, what adults do every minute of every day, it’s quite astounding. And then professor Michael Sawyer is a child psychiatrist who unusually has a real interest in public health so it’s a wonderful team, diverse team, diverse skills.

Interviewer: Melissa, tell us a research anecdote, one which you love to share with colleagues.

Prof Wake: The story of the phantom data. A big part of the study was looking at how children spend their time, so what are their physical activity patterns, and to do this we used a thing called the ‘Time Use Diary’ which is new to child health research. Most time use data is collected for adults and they just write down what they did. What we asked parents to do was to simply fill in circles on a fairly comprehensive grid of their 24-hour day for their kids, and what we found was that children were doing an amazing number of activities and quite incomprehensible and then we discovered this issue with the phantom data. Which was, it turned out to be the scanner being set too sensitive and it was picking up all the little marks on the photo copier and things that simply weren’t there. That kept us busy for about a year working out what that problem was. Anyway it all came good in the end and it’s been much better for every wave since, but that one really exercised us.

Interviewer: Ooh, the scanner that enhanced the data!

Prof Wake: Absolutely. Free of charge too!

Interviewer: Melissa, can you expand on the parenting issues in this investigation?

Prof Wake: This was a big part of the investigation and obviously for pre-schoolers in particular, parents are kind of their world really. They’re not yet at school, the influence of the parents is just paramount and parents I think cop a lot of blame for their children being heavy, you know they ought to feed them better and so on. We really wanted to have a look at whether or not parenting style did influence rates of obesity in this group and because the study is unusual in having data from both the mothers and the fathers separately we were able to look at both maternal and paternal parenting. Very surprisingly to many of our audience we found that the mother’s parenting style really seemed to have no bearing at all on rates of obesity in this group, but interestingly fathers did and this was picked up enormously in the media right round the world. It had television segments etc. on it and I can tell you all the mothers who got interviewed said, ‘yeah it’s all the father’s fault’.

Interviewer: Is it the father’s fault?

Prof Wake: Well, it was a very small effect in fact so we’re not hanging our hats on that. But certainly we felt it was a little bit of a validation of perhaps what mothers are going through who have heavier children.

Interviewer: Professor Melissa will you do it all again and why?

Prof Wake: Well we are doing it all again because the ‘Longitudinal Study’ is continuing. It’s a fantastic resource for all Australian researchers so it’s an open access data base, so anyone with a license can ask any kind of interesting question of all the wonderful data that this wonderful set of parents has provided. So yes I will do it again. At the moment we’re working on trying to add a physical health and bio-marker aspect to the study which will again vastly increase the number of important questions that can be addressed.

Interviewer: I’ve been talking to Professor Melissa Wake, a Chief Investigator of an NHandMRC project. She’s at the Centre for Community Child Health at the Royal Childrens Hospital in Melbourne.

Voice-over: This podcast was brought to you by the National Health and Medical Research Council, working to build a healthy Australia. You’ll find more information about this and other health and medical research issues on our website at www.nhmrc.gov.au.