A genetic variation is associated with a 35 per cent higher chance of obesity. Photo / iStock
A genetic variation is associated with a 35 per cent higher chance of obesity. Photo / iStock
Study says genetics not leading cause, with lifestyle and diet also important.
High obesity rates among Samoans are partly caused by genetics, scientists have discovered.
A new study, published in Nature Genetics today, finds a genetic variation common among Samoans is associated with a 35 per cent higher chance of being obese.
The variation is a mutation on chromosome five, one of23 pairs of chromosomes found in humans. Of the more than 5000 individual samples, taken from volunteers in Samoa, 7 per cent had two copies of the mutation and another 38 per cent had one copy.
The mutation was "virtually nonexistent" in African and European populations and was found to be present at a "very low frequency" among East Asians.
In New Zealand, there were 144,138 Samoans, or 3.6 per cent of the population, at the last Census in 2013.
The Ministry of Health 2014/15 annual health survey says about two-thirds of Pacific adults and almost one-third of Pacific children are obese. Co-author of the study, Professor Stephen McGarvey from Brown University's School of Public Health in the United States, said it was important not to downplay the obesity problem as a genetic inevitability.
While it helped explain why 80 per cent of Samoan men and 91 per cent of Samoan women were overweight or obese in 2010, it was not the dominant factor.
"A healthy diet and physical activity are still key to maintaining a healthy weight."
He explained the genetic variation might have come about as an evolutionary response to Samoans' needs to store fat on long voyages without food in the Pacific.
"Samoans weren't obese 200 years ago," he noted. "The gene hasn't changed that rapidly - it's the nutritional environment that changed that rapidly. Once modern conveniences like motor vehicles and high-calorie foods became prevalent among Samoans, they, like many people around the world, became more prone to obesity."
The study was conducted in Samoa, with the support of the Samoan Government, and analysed samples taken from more than 5000 individuals.
Maurice Wilkins Centre deputy director Peter Shepherd, who is co-leading a similar study of Kiwis, said the robust study proved a need for different strategies to tackle obesity.
"Once people are aware of their risk then they can deal with it ... it empowers them to take control."
Sally Dalhousie, senior manager services at The Fono, a North Island-based health and social services provider, said obesity was a problem among the Pacific community. She found the study's findings interesting, but agreed the genetic variation wasn't the only cause of obesity.
"We find eating is the biggest problem," she said. "Many will go and be physical but then go and gorge themselves. It's a complex issue to do with lifestyle, and the cultural and social aspects of eating."
Obesity gene
• A genetic variation is associated with a 35 per cent higher chance of obesity.
• The mutation is far more common among Samoans than Africans, Europeans or East Asians.
• Researchers believe the gene plays a part in obesity among Pacific Islanders but lifestyle factors, such as diet and exercise, are still more important.
No longer just the 'pretty girls' handbag'
Emmes Ah Young of Auckland has dropped 80kg in just under three years picture. Photo / Supplied
Having her father die, her dog die and breaking up with her partner were the "wake-up" calls one Auckland woman needed to improve her health and lose weight.
Emmes Ah Young, 33 described herself as having always been that "funny fat girl" among her friends, but later at home, in her bed she'd cry.
"I was always the handbag ... to the pretty girls."
In October 2013 her dog died, in November her father had a fatal heart attack, in December she was single.
Then her doctor told the Samoan woman she'd be just another statistic if nothing changed. Ah Young, who weighed 180kg at the time, said his comments finally "hit home".
"It's been a constant struggle," she said. "Being an Islander, it's hard. You are constantly being cooked meals and if you don't eat, there's something wrong with you."
But Ah Young knew she needed to make changes so as not to follow in the family tradition of diabetes and heart disease.
She recalled a dress made for her when she was at her biggest.
"They had to use 2.5m on my dress ... then they had to extend it, because it wasn't enough," she said.
Losing weight was the "hardest thing" as she had to deal with all her emotional and physical issues.
Ah Young started by walking 30 minutes a day then began to "amp things up", attending a gym and getting a personal trainer.
