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.

Mehmet Oz, the Centers for Medicare & Medicaid Services administrator, is ordering all states to step up their efforts to crack down on Medicaid fraud.

His April 21, 2026, announcement expanded on the Trump administration’s related enforcement actions, such as withholding Medicaid funds from Minnesota and threatening to do that for New York, California and Maine.

The Trump administration says there’s a big problem with fraud tied to government-funded care delivered in a person’s home or in the community, officially known as home and community-based services, along with nonmedical transportation, behavioral health and new or high billing providers.

The agency Oz leads is now asking states to immediately “revalidate” providers they claim are “high risk.” That is, states are supposed to require providers to prove that they remain eligible to participate in Medicaid and bill the program. The providers primarily offer at-home care, transportation, behavioral health and other services.

Related legislative initiatives, sponsored by Republicans, are also pending in Congress.

We are health services researchers who study the development and growth of the Medicaid home and community-based services program. One of us (Barkoff) previously served in the role of administrator and assistant secretary for aging of the Administration for Community Living.

We strongly believe that it is sensible and necessary for the government to take steps to prevent, root out and punish Medicaid fraud. But we are mindful that the government’s anti-fraud strategies and tactics could unnecessarily disrupt the very services that people depend on day to day.

We aren’t alone. Many researchers, advocates and policy experts are alarmed by this White House policy.

What’s at stake

All told, Medicaid provides health insurance coverage for about 75 million low-income Americans, including many who are at least 65 years old.

More than 5 million Americans benefit from government-funded home care, which is aimed at keeping low-income people with disabilities and frail older people living in their own homes and communities. Medicaid pays for most home care, covering nearly two-thirds of all such spending in 2023.

When home care works well, people become less likely to have to move into nursing homes or other assisted living facilities. If a home care aide doesn’t show up, the consequences are immediate and can be dire.

An older adult may be unable to get out of bed. A person with disabilities may miss meals or medications. A family caregiver may have to take time off without notifying their employer in advance and lose wages.

That’s why the federal government’s actions – particularly those targeting services provided in a person’s home or community – could endanger millions of people.

Supreme Court ruling

Home and community-based services include help with bathing, dressing, eating, medication management and mobility – services that allow people to remain in their homes rather than moving into nursing facilities. A shift toward home-based care has been underway for decades, driven by both costs and civil rights protections.

One reason for the shift was the 6-3 ruling in 1999 by the Supreme Court in the Olmstead v. L.C. case. The majority affirmed the right of people with disabilities to live in their own homes and communities when possible.

Today, most Medicaid long-term care spending covers the cost of services provided in a person’s home or local community, rather than in an institution. These services cost less and lead to better outcomes. Research and program data consistently show that fraud in these programs is relatively rare.

This is especially true due to safeguards like electronic visit verification, which ensures providers are actually providing services in the home.

Another safeguard in place is that most states contract with and approve fiscal intermediaries, which act as payroll, payment and compliance managers, to make sure that there are verifiable records, payment controls and audit trails in place for the Medicaid program.

Not all ‘improper payments’ are fraudulent

A central problem in the Trump administration’s strategy to root out alleged Medicaid fraud is a basic mischaracterization of many things as fraud that aren’t fraudulent.

Federal agencies are tracking “improper payments” and incorrectly equating them with fraud. The Centers for Medicare & Medicaid Services makes clear that most improper payments stem from documentation errors or administrative issues – not intentional wrongdoing.

The Government Accountability Office, a nonpartisan government agency that produces in-depth research, notes that while fraud does lead to improper payments, the reverse is not necessarily true. That is, improper payments can have a cause besides fraud, such as administrative errors and eligibility processing mistakes.

Blurring the distinction between improper payments and fraud can make it seem like providers are illegally taking advantage of the system. And when that happens, policymakers may turn to blunt solutions that do little to punish actual fraudsters, such as cutting or withholding funding, rather than fixing administrative problems.

Exaggerating the scope of Medicaid fraud

In our view, proposals to overhaul Medicaid’s enforcement methods should be grounded in strong and objective data. Yet much of the argument for structural reform relies on anecdotal examples, isolated cases and select audit findings without broader context.

One of the more egregious cases perpetrated by providers was a home care agency in Pennsylvania that billed fraudulent claims between 2020-2023 totaling US$1.8 million. Another was the Minnesota provider penalized in 2025 after billing for services not delivered.

But those infractions do not justify characterizing an entire category of services that helps tens of millions of Americans remain in their homes as rife with fraud and in need of dramatic changes.

By contrast, as we explained in Health Affairs ForeFront in March 2026, federal oversight bodies – including the Centers for Medicare & Medicaid Services, the Government Accountability Office and the Health and Human Services’ inspector general – produce systematic, data-driven analyses.

These sources consistently caution against equating improper payments with fraud and emphasize targeted approaches to program integrity.

The government designated some 6% of the annual payments by Medicaid as improper payments between 2022-2025, which were worth about $37 billion. Yet, more than 3 in 4 improper payments resulted from insufficient documentation, which usually doesn’t indicate fraud or abuse.

What’s more, Medicaid fraud is regularly subject to enforcement actions. In 2025, Medicaid fraud control units reported 1,185 convictions for fraud nationwide, and combined recoveries from criminal and civil cases totaled about $2 billion.

Emphasis on high-profile cases

Again, a few widely publicized fraud cases in Minnesota and a few other states do not prove that fraud is a chronic problem for Medicaid billing in home care programs.

In an agency as big as Medicaid, which spends nearly $1 trillion annually, some level of fraud will occur. The key question is whether fraud is widespread, systemic or goes unpunished.

Available evidence suggests Medicaid fraud is none of those things.

For example, large-scale home care programs serving hundreds of thousands of people report extremely low rates of confirmed fraud cases. Enforcement data from Medicaid Fraud Control Units, which investigate and prosecute Medicaid fraud, show that when fraud occurs, it is investigated and prosecuted.

In other words, the presence of enforcement activity is evidence that oversight systems are working – not that they’re failing.

A better approach

We believe that many strategies that are better than those that the Trump administration is embracing are readily available. Some examples include improved data analytics, stronger referral systems within managed care plans, enhanced provider screening and documentation standards, and continued support for Medicaid Fraud Control Units.

These approaches target fraud directly without jeopardizing access to the essential Medicaid services that help tens of millions of older adults and disabled people remain where they want to be: in their own homes instead of in more expensive nursing homes.

Given that the U.S. spends about $930 billion a year on the program, we don’t question the wisdom of engaging in its oversight.

But we are concerned that the policy response to alleged fraud could harm the very people that the Trump administration says its efforts are meant to protect.

Marc Cohen receives funding from the RRF Foundation for Aging.

Alison Barkoff receives funding from the Commonwealth Fund.

Jane Tavares receives funding from the RRF Foundation for Aging.

Sara Rosenbaum receives funding from the Commonwealth Fund.