Early start to beat obesity

Image of Dr Li Ming Wen

As early as two years of age, one in five toddlers in Australia is already overweight or obese.

With accumulating evidence that excess weight and fast weight gain in early childhood are related to being overweight in later life, how soon should we intervene to halt the progression?

Dr Li Ming Wen from the School of Public Health and Sydney Local Health District, argues that efforts to prevent childhood obesity should begin in the early years and even before birth. He is the principal investigator in the Healthy Beginnings trial, a major public health intervention with first-time mothers and their babies covering the first two years of the baby’s life.

The trial is an international ‘first’ and has attracted over $1.2 million in NHMRC funding over six years. “Most trials deal with obesity and overweight in school-aged children. That’s too late,” says Wen. “It’s much easier to gather school-based information, so researchers may try to avoid younger children.”

Gathering study participants for his trial was definitely a more difficult process, with recruitment taking almost a year to complete. Even then, he started with 667 pregnant women, and lost 170 to follow-up (equally spread across the intervention and control groups). An early risk for children becoming overweight/obese is overweight mothers. Apart from the genetic issues, mothers affect their offspring directly through the lifestyle and environment they provide for the child, and indirectly in the behaviour they model. “We have to start early to engage mothers. Their physical activity, whether they smoke or not, and their nutrition, are the three major maternal behaviours impacting on the weight of babies in the first months.”

Interestingly, while low birth weight is often associated with mothers who smoke, the higher rate of overweight and obesity in children of mothers who smoked during pregnancy is also observed. Wen says that it’s not quite clear how the mechanism works, possibly it can be explained by a cluster of health risk behaviours associated with the smokers.

The two year randomised controlled trial was conducted in south west Sydney between June 2007 and December 2010. Women in the intervention group received eight home visits from community nurses. The first visit took place before the birth, with subsequent visits timed to correspond with early childhood development milestones (1, 3, 5, 9, 12, 18 and 24 months). “In contrast with previous studies, the unique aspect of this study was that the intervention dealt with several risk factors for early obesity in a systematic and timely fashion, including infant feeding practices, children’s eating habits, and sedentary behaviours,” says Wen.

The key intervention messages included:

  • Breast is best
  • No solids for me until six months
  • I eat a variety of fruit and vegetables every day
  • Only water in my cup
  • I am part of an active family
  • TV away, let’s go play

“There is continuing evidence that the longer the duration of breastfeeding and exclusive breastfeeding, the greater the reduction in risk for overweight and obesity, at least in the short-term, in addition to many other health benefits. And yet, some mothers are starting their children on solids as early as two or three months,” says Wen. He’s also concerned that parents use food as an encouragement for good behaviour.

“We want to follow up on these children at age five, to see if there is a long-term effect from this early intervention. There are no studies in this area looking at long-term effects.” While maintaining a healthy nutritional regimen is something within parental control for babies and toddlers, introducing physical activity is not always so easy. How do you make a baby who can’t yet walk,‘shake, rattle and roll’? Wen’s group called for ‘tummy time’ moving a baby from lying on their back or reclining in a chair, to a position where they are free to move and crawl.

As children get mobile, they need to be encouraged to be active. “Mothers are so busy in the first two years, they often turn on the TV as a babysitter so they can get things done around the house. We tried to get mothers to turn off the TV and let kids play outdoors. “Another issue for our trial group was that half the participants live in units where there is no backyard or park nearby,” says Wen. He’s interested in doing further research into vertical living and whether residing in apartments has any effect on outdoor play and activity.

The good news from the Healthy Beginnings trial is that early intervention can lead to a reduction in BMI at two years of age. The mean BMI was significantly lower in the intervention group than the control group. In addition, 11.2% of the intervention group were categorised as overweight or obese, by comparison with 14.1% in the control group. There were also secondary outcomes from the trial which showed further health benefits from the intervention. There was a positive effect on children’s vegetable consumption and reduced time spent watching TV.

The other significant benefit was experienced by the mothers - not surprising as the trial focussed on healthy family life as a whole. Mothers in the intervention group were significantly more likely to eat more than two serves of vegetables a day than those in the control group, and to spend 150 minutes or more a week on physical activity than those in the control group. Since the lifestyle of the mother becomes the lifestyle of the child, improved maternal nutrition and activity is likely to reinforce the benefits already accrued by children who have had a healthy start to their lives.

Dr Wen and his team are currently conducting phase 2 of the Healthy Beginnings trial which is also funded by an NHMRC project grant. The aims are to determine if the Healthy Beginnings trial intervention will lead to a lower mean BMI, lower screen time, improved dietary behaviours and demonstrated cost-effectiveness of the intervention, in children aged three and a half and five years. The study protocol was published in Contemporary Clinical Trials in 2012.