Consumption of ultra-processed foods – including soft drinks, snacks and ready meals – is growing worldwide, despite evidence they are unhealthy.

Ultra-processed foods (UPFs) make up about 70% of packaged food products on supermarket shelves, and even more in convenience stores.

In our new research, we explore how companies that produce these foods play on human nature to make such products seem the easiest, most rewarding and compelling option.

We show that UPFs are designed to make us crave them and eat more. They are marketed to all groups, particularly children, in a way that makes them seem the most delicious and convenient option, giving the best value-for-money, despite many health harms.

Our attraction to UPFs is no coincidence. UPF companies combine a range of tactics to drive up consumption. Many of these tactics exploit the ways we think, feel and behave.

Why we keep eating UPFs

UPFs are the most processed foods on the market. According to medical journal The Lancet, they are commercial formulations made from cheap ingredients extracted or derived from whole foods, combined with additives, but mostly containing little to no whole food in the end product.

UPFs are heavily branded and marketed, and most are produced by large international corporations.

But diets high in UPFs carry a risk of developing a wide range of serious health conditions, including excess weight or obesity, type 2 diabetes, hypertension, heart disease, cancer, chronic kidney disease and depression, as well as premature death.

Our research asked why we keep eating diets high in UPFs when we know how unhealthy they are. To answer this, we decided to zoom out and explore the system that develops, produces and markets UPFs, and investigate how human nature is caught up in it.

We reviewed a decade of published research on the food science and marketing of UPFs, and then worked with experts in these fields to create and refine system diagrams to visualise how it works.

These maps are called “causal loop diagrams”, and their power is in showing reinforcing (positive) feedback loops that drive the system towards its ultimate purpose: selling more UPFs.

We found the system is made up of many interconnected loops that capture parts of human behaviour and biology as key elements.

Products designed for maximum consumption

One feedback loop includes the use of addictive combinations of ingredients, particularly refined carbohydrates and fats. Biologically, carbohydrates (including but not limited to sugars) and fats activate different reward pathways between the gut and brain. When they are consumed together, their effects become addictive.

These ingredients can be combined in many different concentrations to hit sensory “sweet spots”. In other words, they maximise pleasure and craving responses while minimising negative responses.

Further strategies include processing methods that suppress peoples’ natural sense of being full or speed up digestion in order to give an immediate but quickly fading sense of “reward”, making us want more, sooner.

UPF marketing strategies

In terms of marketing, products are formulated to be easy and convenient to store and eat, and to appeal to our sense of getting good value.

Various promotional techniques aim to capture consumers’ attention and desire, as well as giving the illusion of healthiness. Strategies targeting children in particular employ popular culture associations with coolness or fun.

Another example of a feedback loop is how corporations collect large and complex data on our purchasing habits and our online lives, informing targeted digital marketing on social media platforms. This tends to be effective at driving purchases, providing more data to further refine these promotion strategies.

Overall we identified 11 different reinforcing feedback loops. Our research is the first study to show this web as part of the UPF system, designed to essentially trap people into buying and eating more and displacing healthier options in diets.

This product-level system also connects with feedback loops further up the supply chain in economic and financial spheres of the global UPF production.

This matters because unhealthy diets and excess body weight cause 18% of preventable premature death and disability in New Zealand. Both risk factors are linked to eating too much UPF.

Unfortunately, New Zealand hasn’t undertaken national nutrition surveys since the 2000s and we have to rely on data from similar countries such as Australia to estimate that UPFs make up about half of our energy intake.

What to do about it

Diets high in UPFs are not the result of people’s free personal choice or weak willpower, but of an intentionally designed system.

Our research shines light on how the UPF system is taking advantage, particularly of children. International experts have framed UPFs as a major global health issue, and advise strong government policy to regulate these products to counter some of these mechanisms.

Policy leadership already exists in other parts of the world, particularly in Latin America. New Zealand could follow other countries that have implemented taxes on UPFs and sugary drinks, regulations restricting advertising to children, strong front-of-pack labelling and transparency policies such as public disclosure of lobbying in government.

Complacency is not an option. The food system needs rebalancing so that it serves and nourishes people now and in the future.

The authors acknowledge the research contribution by Dr Joshua Clark.

Kelly Garton receives funding from the New Zealand Heart Foundation. She is affiliated with the advocacy group Health Coalition Aotearoa.

Boyd Swinburn is affiliated with the Health Coalition Aotearoa.

Few things matter more to us than our eyesight. We fear losing it even more than some life-threatening conditions.

Yet for many New Zealanders, access to routine eye care remains out of reach. This is despite the wide-ranging impacts of vision loss for both individuals and society.

It limits opportunities for work and study, raises the risks of traffic accidents and falls, and is linked with higher rates of depression and dementia. Globally, the annual cost in lost productivity has been estimated at nearly NZ$700 billion.

What’s more, it is mostly avoidable. More than 90% of vision loss can be prevented or treated with simple, cost-effective care such as glasses or cataract surgery.

In dollar terms, providing funding for spectacles and eye examinations for New Zealanders could provide a $36 benefit for every $1 spent.

If Aotearoa matched Australia’s public funding policies for community eye care, allocating just 1.2% of its health budget could fund 2.4 million eye examinations and 60,500 pairs of glasses. Current funding delivers eye care services to 25,000 children for about 0.02% of the health budget.

With the government now deliberating its 2026 health budget, our preliminary research looks at what it could cost to make routine eye care a reality for all New Zealanders.

A plight out of sight

Anyone reading this article in New Zealand through a pair of $2 reading glasses isn’t alone in choosing cheap solutions to improve their vision. As many as one in four Kiwi patients may be skipping or delaying specialised eye care because of the cost.

Routine eye examinations and spectacles are delivered almost exclusively by optometrists in private practice, with very little public funding to offset the costs.

This places New Zealand behind other countries, including Australia, the United Kingdom, Ireland and the United States, which fund routine eye care for some or all of their population.

For Kiwis needing financial support for eye care, options are limited. The children of Community Services Card holders can access up to $287.50 for an eye test and glasses via Enable New Zealand.

People on low-incomes can apply for a $280 loan from Work and Income New Zealand, which must be repaid. Spectacles are not currently available in the public sector. Despite advertised “$0 eye tests” and discounted spectacles, the reality is that eye examinations and spectacles remain unaffordable for many.

Optometry services provide more than a new pair of frames. Regular eye examinations are essential to detect and treat progressive conditions such as glaucoma and diabetic retinopathy which are asymptomatic in their early stages.

By excluding this preventative eye care from the public health agenda, New Zealand is leaving some communities to live with an avoidable burden.

In particular, eye care services are two to three times less accessible for Māori and Pacific people than for other New Zealanders.

One recent study found that in an inner-city Auckland community with a high Māori and Pacific population, half of residents with vision loss had never had an eye examination, while three-quarters had never been prescribed custom spectacles.

Should NZ adopt Australia’s model?

If New Zealand seeks a fairer model for eye health, policymakers have only to look across the Tasman.

In Australia, all citizens and permanent residents are eligible for Medicare-funded, comprehensive eye examinations delivered by optometrists.

Around one-third of its population uses these services every year. Uptake is highest among older adults, while additional policies target Indigenous Australians, for example via state-funded spectacle subsidies.

If New Zealand saw similar uptake, we estimate that adopting a comparable model would cost around $349 million a year, funding approximately 2.4 million eye examinations.

An additional $13 million would deliver around 60,500 spectacles to people who need them the most. Even this generous costing is comparable with other health investments, such as the Labour Government’s 2023 proposed investment of $390 million to extend free dental care to approximately 800,000 19–30 year olds.

Universal funding is not the only option: more targeted approaches could prioritise those at greatest risk of avoidable vision loss.

For instance, our analysis indicates that public investment of $89 million could subsidise approximately 760,000 examinations for Community Services Card holders who are most likely to need financial support.

Just $37 million would fund eye care for children under 15 years, aligning with universal dental and GP services for this age group. At the other end of the age spectrum, around $166 million per year would support eye care for older adults, who have the greatest need.

This investment would arguably be more effective than the $61 million proposed within the 2020 health budget to fund one-off “eye health checks”, for which there is no evidence of population-level benefit.

Healthy eyes should not be a luxury. New Zealand can and should include eye examinations and spectacles within its health expenditure.

Preventative eye care is a cost-saving investment that will reduce the societal and economic impacts of vision loss. For policymakers, it as an opportunity to invest in an area of health that has remained out of sight for too long.

Lucy Goodman receives funding from the Health Research Council of New Zealand.

Jacqueline Ramke has received research funding from the Health Research Council of New Zealand, Buchanan Charitable Foundation and the New Zealand Association of Optometrists.

Pushkar Silwal has received funding from Health Research Council of New Zealand.

In New Zealand’s long and storied romance with the property market, the “mum and dad” investor has always been a central character.

With equity ready to draw on, they’ve traditionally accounted for between a third and half of all residential sales – driving a flow of bank credit, but also a steady rise in house prices.

In 2026, however, there are strong signs these market movers are sticking to the sidelines, or getting out of the game altogether.

A recent survey of 200 mum-and-dad landlords by independent economist Tony Alexander points to a sharp shift in sentiment, with a record number (38%) planning to sell and relatively few (12%) seeking to buy.

The latest Cotality data suggests they’re still somewhat active in the market – investors with mortgages were behind a quarter of national sales in the first quarter of the year – but not at the levels seen in the past.

At the same time, various pressures have been changing the economics of property investment.

Those 200 surveyed investors singled out concerns about higher running costs, rising council rates, ongoing challenges in securing reliable tenants and economic uncertainty over the Iran war.

That uncertainty is further illustrated by new figures showing sellers have been slashing asking prices by tens of thousands of dollars, with some still trying to offload houses they bought at the market’s 2021 peak.

For many smaller investors, it appears the model that once relied on steady capital gains is becoming harder to sustain.

Credit, costs and a changing market

In New Zealand and around the world, arguably the single biggest driver of housing markets is bank credit, or debt.

Real estate values depend not only on supply and demand, but also on the purchasing power of buyers. As few people have enough cash to purchase property outright, most rely on bank credit.

Housing market commentators often benchmark New Zealand prices against their peak in late 2021. This happened to coincide with amendments to the Credit Contracts and Consumer Finance Act, which tightened how banks assess lending affordability.

Although politicians reversed course six months later, the restriction in housing credit reduced homebuyers’ aggregate purchasing power. House prices have yet to recover to their 2021 highs.

Another squeeze on housing credit came with the Reserve Bank’s debt serviceability restrictions, called debt-to-income limits. These cap how much borrowers can take on relative to their income: six times income for owner-occupiers and seven times for investors.

While these limits weren’t formally introduced until mid-2024, they were added to the Reserve Bank’s policy toolkit during the market’s June 2021 peak, with banks phasing them in gradually.

At the same time, two-year fixed mortgage rates more than doubled, from 3.46% in April 2021 to 7.60% in October 2023. Right now, they’re sitting closer to the mid-5% range, easing from their peak – but still well above recent lows, with a risk of further hikes.

With the housing boom now fading into the distance, many New Zealanders are confronting an uncomfortable reality: house prices do not always rise, and capital gains are not guaranteed.

That caution is already showing up in the data.

Recent figures point to softer sales volumes and subdued buyer activity, with rising borrowing costs and wider economic uncertainty – including the prospect of further inflationary pressure from the Middle East crisis – weighing heavily on confidence.

The current market malaise affects everyone, but mum-and-dad investors arguably face the toughest conditions. Without capital gains, rental property can be a poor investment given the risks involved.

A reset for the housing market?

For investors having to top up mortgage payments out of their own income because rent no longer covers the costs, the warning signs are clear.

Because these investors are major users of mortgage lending – often borrowing against existing equity to buy more property – a large-scale exit would slow the flow of housing credit that has long underpinned rising prices.

That would be disruptive and destabilising to what has long been a key plank of New Zealand’s economy. Yet a pullback by small-scale investors could also have positive effects elsewhere in the market.

New Zealand is grappling with deepening housing inequality, with a widening divide between those who own property and those locked out of it.

Average house prices may have fallen over recent years, but they still sit at around 7.2 times the median household income. In some regions, such as Queenstown Lakes and Thames-Coromandel, price-to-income ratios remain well into double digits.

With fewer investors competing for existing homes, price pressures could ease, improving access for first-home buyers, encouraging more stable, institutional build-to-rent developments and shifting the market away from speculative gains.

There may also be opportunities to redirect capital into more productive uses.

Funds withdrawn from housing could instead flow into lower-risk, income-generating assets such as Kiwi Bonds or other government-backed investment vehicles, offering steadier returns while supporting broader public investment.

That kind of shift could provide investors with steadier returns, while helping rebalance a housing system that has long relied on ever rising prices.

Michael Rehm has received research funding from the Ministry of Business, Innovation and Employment.