The spread of fast food chains in cities may not be behind a global rise in obesity, but rather weight gain in rural areas could be responsible, according to a new study.
Members of NCD Risk Factor Collaboration, an international group of scientists, have analysed 2000 studies of more than 112 million adults to understand an increase in global obesity since 1985.
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The research found around two-thirds of the increase in the global mean Body Mass Index (BMI) can be attributed to BMI rises of people living in rural areas.
The BMI of an individual is a height-to-weight ratio commonly used to measure obesity.
This challenges the view that urban lifestyles have greatly contributed to a more obese society. It was largely believed that city life had contributed to the increase as a rise in BMI over the last few decades paralleled more people moving to urban areas.
University of Auckland Popular Nutrition Professor Boyd Swinburn told The AM Show the weight gain was a significant insight into the rural community.
"People living in urban areas still have more obesity when you look at the globe, but it is this catch-up, this last 30 years, where previously rural populations have been relatively lean, and now they have been influenced by the obesogenic environment and they are gaining weight rapidly," he said.
In low- to middle-income regions, more than 80 percent of the rise in BMI was due to rural populations.
With the exception of women in some parts of Africa, BMI has risen in rural areas at the same or faster rate than in cities.
But Prof Swinburn said in New Zealand, the rise has been similar between rural and urban communities for the last 30 years.
The study said the results suggested public health policy globally may need to change to ensure people in rural areas have access to healthy foods.
Study co-author Majid Ezzati said people in rural areas may be putting on weight due to industrialisation. For example, people don't need to walk to a well to get water and don't need to walk into town due to cars. This technology is becoming increasingly cheaper in these areas.
There are also fewer gyms and sports facilities in rural areas for frequent exercise.
"I think it is a real mixture isn't it, and the things that obviously drive it around the junk food and the mechanisation and wealth, increasing wealth and availability to buy things is now hitting the rural communities," said Prof Swinburn.
It may also be more difficult to get educational information about nutrition, health fads, or the need to exercise to those in rural communities without internet.
"There is a wave of people being more health aware and practicing healthy behaviours, [that's] more likely to land first in Takapuna than it is in Taihape."
He criticised the Government's action on obesity saying it was doing little to tackle the issue.
"There is nothing concrete at the moment on the table for obesity prevention, things like restricting junk food marketing to kids, things like healthy food in schools policies, that may come in the budget, I hope it does."
He said Health Minister David Clark had asked food companies to step up and was hopeful action came from consultation between the parties.
A 2018 study by Otago University found two million Kiwis will be considered obese by 2038 if the epidemic isn't curbed.
It found the average BMI went from 26.4 to 28.3 between 1997 and 2015 - a significant increase. It was worse for Māori and Pacific people, and those living in social deprived neighbourhoods.