Otago researchers reveal childhood predictors of adult obesity

International research findings have already suggested at a number childhood determinants of adult weight and obesity, however, less is known about the New Zealand context and the University of Otago research published today in the latest issue of the New Zealand Medical Journal provides some answers.

The research is from the longitudinal study carried out in the Christchurch Health and Development Study. It spanned over 40 years and monitored 1265 children who were born in Christchurch in 1977, until they reached the age of 35, using a combination of interviews with the participants and parents, standardised testing, teacher reports and official record data. 

Obesity statistics in New Zealand are on the rise, with the adult obesity rate increasing from 27% in 2006/07 to 32% in 2016/17 and people living in low income areas with the highest risk of obesity. A survey from the Ministry of Health in 2017 shows that Māori and Pacific Islanders also have a significantly higher risk of becoming obese. 

The results showed that by the age of 30 and 35 about one-third of the people surveyed in the study had become overweight, with one-fifth classified as obese. 

Some of the factors identified as being predictors of becoming overweight or obese as adults were being male, born into a single-parent family, having parents with larger body size, limited or no breastfeeding when a baby, higher early infant growth, lower levels of cognitive ability and exposure to severe sexual abuse.

Director of the Christchurch Health and Development Study and one of the researchers for this project, Professor John Horwood, says none of the findings are particularly surprising and are in line with international evidence.

“The findings confirm that risk of obesity is related to a complex mix of factors reflecting biological endowment, socio-economic disadvantage, early diet and adverse childhood experience,” Professor Horwood explains. “Individually, the identified risk factors have a relatively modest impact on adult weight, but jointly they can add up to something that is substantial,” 

“So, if you have three or more risk factors there is likely to be an associated increased risk of obesity.”

Most of the factors identified in the present study (such as gender, parental BMI and exposure to childhood sexual abuse) are not amenable to change or modification in the context of obesity prevention, the research paper states.

The exceptions to this were the findings for longer duration of breastfeeding and weight gain in infancy, which have been shown in a number of studies to be associated with lower risk of adult obesity.

This suggests that strategies such as the promotion of breastfeeding, the encouragement of longer duration of breastfeeding, monitoring the use of formula and limiting the early introduction of solid foods could play key roles in any strategy designed to reduce obesity, the researchers say.

In New Zealand there are a number of providers such as Plunket, Early Start and Family Start which deliver a range of home visiting, child health checks, maternal education and resources to families with young children. The researchers suggest it may be possible to integrate evidence-based early intervention for gaining weight through these or similar agencies.

The New Zealand Health Strategy aims to reduce population levels of obesity and the associated health and financial costs. Several approaches are identified in the strategy to support this goal including sport programmes, public education and better food labelling.

For further information on this research contact

• Professor John Horwood,
  Director, Christchurch Health and Development Study