Scientists have known for some time that Pacific islanders are more prone to obesity than people in other nations. Now a new study led by the University of Oxford has examined why islanders on Nauru and in the Cook Islands in the Pacific have the highest levels and fastest rates of obesity increase in the world. On both the islands, between 1980 and 2008 the increase in the average body mass index was four times higher than the global average. The paper, published in the journal Public Health Nutrition, provides a novel theory for why obesity levels are so high there. It suggests that social changes, introduced when the islands were under colonial rule, have significantly contributed to unhealthy dietary habits.

The Cook Islands were taken as a British protectorate in 1888, and became New Zealand's first South Pacific Island colony in 1901 until political independence in 1965. Meanwhile, the tiny Pacific island of Nauru is a former German and British colony whose Administration was led by Australia until 1968. Anthropologists Dr Amy McLennan and Professor Stanley Ulijaszek at the University of Oxford scoured existing academic literature and archive documents about the islands from libraries in Australia, Nauru and the UK. They also interviewed people on the the islands and lived there themselves for a short time to observe daily life first-hand.

Their research paper shows that historical materials and memories reveal the extent to which the colonial settlers changed the lives of the islanders. It quotes colonial letters describing how the settlers taught ‘proper’ food habits as part of their attempt to ‘civilise’ the islanders. The paper says this is one reason why islanders lost many of their traditional food growing and food preparation skills. This was also when the islanders’ dependency on imported food began. Food began to be prepared in line with ‘colonial conceptions of socially-proper behaviours and health diets’, says the paper. It suggests that the social changes happened very quickly because of the islands being small and populated by close-knit communities. Given food preparation and eating is usually a communal process there, the particularly strong social ties between the islanders could be one reason why obesity levels have risen so quickly in recent times, says the research.

When islanders started to depend on imported food, traditional skills in fishing or food preparation were lost, says the paper. In their place came an increase in energy-dense, nutrient-poor food products. Islanders were taught to fry their fish rather than eat is raw as they had done before colonial rule. Colonial initiatives, such as mining or cash-crops, meant that land historically used for food gathering became inaccessible or infertile, says the paper. It adds that pollution from colonial shipping lines and industry degraded reefs, a former rich food source.

The study says another reason for the islanders ‘disproportionately’ importing more food has been the rapidly growing populations on the islands. Again the paper argues that colonial leaders played a part in changing the culture, encouraging large families after previous population declines due to outbreaks of infectious diseases in the late 1800s and early 1990s.

Lead author Dr Amy McLennan said: ‘Under colonial rule, much changed in how food was sourced, grown and prepared and the social change was swift. What happened to the land also changed as colonial agriculture and mining industries expanded. There was an increase in family size meaning food was increasingly imported. The good news is that if obesity is tackled across the whole community not just amongst people labelled as ‘obese’ -- dietary habits could change quickly again. Lessons learned from the experiences of these smaller nations could also help us to think in new ways about social change and obesity in larger societies.’

Professor Stanley Ulijaszek said: ‘Previous attempts to explain the disproportionately high rates of obesity in these and other island nations have tended to focus on the geographical isolation of islands and the risk of food shortages. Theories have suggested that islanders are genetically predisposed to putting on weight, but we believe this does not explain why obesity has emerged so rapidly on these islands. Interventions that tap into the naturally occurring social networks on the islands provide a new, and we believe more effective, way of tackling obesity.’

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