The findings are part of a study by the University of Otago’s Christchurch Health and Development Study (CHDS). The Health Research Council-funded research group has tracked the health and psychosocial development of more than 1000 children born in Christchurch in 1977.
CHDS director Associate Professor John Horwood says international research suggested a possible link between obesity and poorer mental health and well-being. So his group studied its participants at age 30 and 35 to see if they could find evidence of the link in New Zealanders.
They analysed the relationship between a person’s size, using the BMI Index, and outcomes such as net weekly income, savings, household income and depression and life satisfaction. The findings have been published in the Social Psychiatry journal.
Associate Professor Horwood says they found being overweight or obese was associated with poorer outcomes, but only for women. “There was a small but pervasive relationship between increasing body size in women and lower income, depression, low self-esteem and dissatisfaction with life.”
“We found an interesting relationship in terms of a person’s size and their income. There was a clear relationship between larger men and larger weekly pay packets (see table 3 ‘mean personal income – weekly net NZ dollars in attached journal publication). But for men, being classified as overweight or obese according to the BMI Index did not negatively affect other outcomes measured in the study such as self-esteem or mental health.”
The researchers found men with a BMI of more than 30 – the classification for obesity – earn on average $140 a week more than males with a normal BMI. Women classified as obese on the BMI Index earn on average $60 less than women with a ‘normal’ BMI rating (table 3).
Associate Professor Horwood says there are limitations with using the BMI Index. For example, the BMI Index can classify a large, muscular man as being obese.
He says the study was designed to establish relationships between size and psychosocial outcomes rather than explain them. There is likely to be a range of reasons behind the findings, particularly why obese and overweight women earn less and have poorer mental health. One reason could be Western society’s general view that female obesity is undesirable and unattractive. Another could be growing evidence to suggest women are more responsive to adversity in life than men. Not only is there more stigma attached to weight and body composition for women but they may also be more likely to perceive being overweight or obese as a source of stress or adversity.
Associate Professor Horwood says he hopes to revisit the study when the participants were older to see whether the links they found persist over time.
For more information, contact:
Associate Professor Horwood
University of Otago, Christchurch
Tel 03 378 6441