Obesity rates level off in NZ – at high rate

Obesity levels have risen in 200 countries tracked by researchers over the past 45 years, including Aotearoa, New Zealand, which has recently flattened off.

The study by a global NCD Risk Factor Collaboration (NCD RisC) analysed measured height and weight data from more than 232 million people across 200 countries and territories between 1980 and 2024. See Nature.

“We see some discernible patterns emerging,” says Professor Boyd Swinburn at Waipapa Taumata Rau, University of Auckland who is part of the consortium and has written a commentary to accompany the study.

“Obesity has increased in almost every country over the past 45 years but is now rising fastest in poorer nations.

“New Zealand is part of a group of high-income countries with increasing obesity for the full 45 years up to a high level but with recent flattening.

“Other countries have later entry into the epidemic and experienced more  recent acceleration.”

Like New Zealand, parts of western Europe, North America and Australasia  experienced earlier growth in obesity, with rates now slowing in many places.

By contrast, countries in South and South‑East Asia, Africa and parts of Latin  America are seeing much steeper increases, despite starting from lower levels.

Despite decades of research and policy efforts, the overall global trend has been relentlessly upwards. Professor Swinburn says this reflects a powerful force shaping food environments worldwide.

“We have this huge global force pushing obesity onto countries and  populations who actively do not want it, but it keeps pushing.”

The commentary points to ultra‑processed foods as a key driver. These products are typically made from cheap ingredients using industrial processes, contain high levels of sugar, salt and fat, include cosmetic additives, and are marketed aggressively.

“A Lancet Series, a landmark study, on ultra‑processed foods gave the clue to what that huge industrial force is likely to be,” Swinburn says.

Ultra‑processed foods now dominate diets in many parts of the world and are strongly linked to rising obesity, diabetes, heart disease, depression and other chronic conditions.

In New Zealand, it is estimated that around half of daily energy intake comes from ultra‑processed foods, similar to other developed countries.

More recent research from the University of Auckland has shown how ultra‑processed food manufacturers deliberately design products to exploit human biology and psychology, driving ‘passive overconsumption’ and higher profits.

“Countries with strong traditional food cultures, particularly in parts of Europe, may be somewhat protected because ultra‑processed foods have not  displaced home cooking to the same extent,” Swinburn says.

The new global data also support the idea of an ‘obesity transition’, where obesity initially affects higher‑income, urban women, then spreads to men and children, before becoming more prevalent among lower socio‑economic  groups.

Some high‑income countries may now be entering a further stage in which obesity prevalence begins to decline, possibly because leaner children are ageing into adulthood.

“These patterns matter because they show obesity is not an inevitable outcome of economic development,” Swinburn says.

“Rising national wealth enables obesity to increase, but it does not dictate the outcome: culture, food systems, media and policy choices all play a role.”

For New Zealand, Professor Swinburn says the experiences of countries that have avoided large rises – or are starting to reduce obesity rates – offer important lessons.

“We need to look at other high‑income countries like Japan, France, Portugal and Italy, which have not had big rises in obesity like New Zealand and are just starting to reduce their prevalence.

“It has a lot to do with protecting traditional cuisines and dietary patterns based on real foods.”

It is urgent for countries including Aotearoa, New Zealand to strengthen policies that support healthier food environments before current plateaus are reversed.