Weight loss medication is no substitute for food regulation

New Zealand has an obesity problem. But help might soon be at hand. GLP-1 weight loss medication is now widely available in the US, with mounting evidence of their effects on patients’ diets and subsequent weight loss. They are now available in New Zealand, albeit at significant cost to the patient. But in my view they are treating the symptom rather than addressing the cause, and while they will undoubtedly play a role in managing chronic dietary-related conditions such as type 2 diabetes and cardiovascular disease, better food regulation is a more sustainable solution to improving diets and health.

Based on the New Zealand Health Survey, the Ministry of Health reports that over the year to June 2025, one in three (34%) New Zealand adults were obese with a Body Mass Index (BMI) of 30 or above (see Chart 1). One in eight children were also obese. Obesity rates among adults have been rising steadily over time. Rates among children have been steady over time with year-to-year survey results not statistically different.

Even more concerning is that obesity rates among Pacific and Māori adults are higher with almost three-quarters (70%) of Pacific adults and almost half (47%) of Māori adults obese over the year to June 2025.

New Zealand also compares poorly with other developed countries. In 2023, the OECD reported that an average 26% of adults across all OECD countries were obese compared with 34% in New Zealand.

The OECD notes that individuals who are overweight or obese have a higher risk of developing type 2 diabetes, cardiovascular diseases, fatty liver disease, certain forms of cancer, and dementia. 

GLP-1 medications are prescription drugs that mimic a natural gut hormone to help control blood sugar, reduce appetite, and increase feelings of fullness after eating. Originally developed to treat Type 2 diabetes, GLP-1 medications are now widely used to support weight management.

GLP-1 weight loss medications have quickly gained a foothold in the US. A 2026 survey found that 11% of U.S. adults currently take GLP-1 medications for weight loss, up from just 3% in 2024.

In a recent systematic review of existing literature, researchers in the US found that GLP-1 medications produced a mean weight reduction of 4.57kg. And the benefits extend beyond weight loss. For example, other studies have found that GLP-1 medications caused a reduction in major adverse cardiovascular events, as well as obstructive sleep apnea. There’s also early evidence that GLP-1 medications can reduce some obesity-associated cancers, though the evidence remains mixed.

The mechanisms by which the weight loss occurs is still being studied. Research based on self-reported changes in diet suggests that GLP-1 medications result in lower cravings for dairy and starchy foods and less desire to eat salty, high-fat, sweet, savoury or spicy foods, along with less difficulty controlling eating and resisting cravings. Further research that uses objective measures of food intake is needed to support these claims.

GLP-1 medications have recently become available in New Zealand. Medsafe has approved several GLP-1 medications, though none are currently publicly funded by Pharmac. Cost is therefore a barrier for many patients. For example, a GLP-1 medication called Wegovy currently costs between $450 to $630 a month.

Wegovy was launched in New Zealand on 1 July. Between 1 July and 29 October 2025 (the latest figures available), 18,178 people were dispensed at least one month's supply of Wegovy. Even if these medications receive Pharmac funding, there are limitations on who can prescribe them and who they can be prescribed to, but public funding will likely result in their growth, nonetheless.

In New Zealand, the direct health care cost of obesity is about $2 billion a year and the indirect cost, such as loss of productivity, is between $7 billion and $9 billion a year, according to 2021 research by Sapere. If GLP-1 medications take hold in New Zealand the way they have in the US, they could result in a net cost saving to the health system as the cost of funding the medication is more than offset by reduced costs of treating type 2 diabetes and other dietary related health conditions. The medication could also have a positive effect on GDP, incomes, and people’s overall quality of life.

Food demand might also shift away from confectionary, chippies and other snacks, fast food, desserts, sugary drinks, and high-fat foods towards fresh fruit and vegetables, leaner protein, higher-protein foods, smaller portions and foods consumed for nutritional purposes rather than pure reward. Local food producers, supermarkets and other grocery stores, fast-food outlets and restaurants might see a noticeable shift. If these medications catch on worldwide, our food exporters could also be affected.

Why regulate what food companies produce when consumers now have an effective medical technology for controlling their consumption? It’s a fair question to ask, particularly if food companies respond to any shift in food consumption, pivoting production towards products specifically designed for the GLP-1 consumer.

But in my view, that is missing the point. Some aspects of the food environment in New Zealand, as in many other countries, have become detrimental to the nation’s health. A series of three papers published in The Lancet, a medical journal, in 2025 reviewed the evidence about the increase in Ultra-Processed Foods (UPFs) in diets globally and found that UPFs are displacing long-established diets centred on whole foods and that this pattern increases the risk of multiple diet-related chronic diseases. Research published in Nutrients in 2020 reviewed 43 studies and found 37 of them linked UPF exposure with at least one adverse health outcome. These included overweight, obesity and cardio-metabolic risks; cancer, type-2 diabetes and cardiovascular diseases; irritable bowel syndrome, depression and frailty conditions.

The increasing dominance of UPFs isn’t surprising. UPFs tend to be highly profitable, made from cheap ingredients using industrial methods, contain a lot of sugar, salt, fat and additives which make them highly palatable, and are heavily promoted by food companies. UPFs are usually cheap and convenient to prepare for eating so they make economic sense for households short on time or money. They also tend to have long-shelf lives which makes them easier to store and transport, and reduces wastage at retail outlets and in households.

There hasn’t been a nutrition survey in New Zealand for many years, so we don’t have hard figures on UPF consumption. Professor Swinburn, who authored one of the three papers published in The Lancet and who is co-chair of Health Coalition Aotearoa, estimates that UPFs make up 50%-60% of the nation’s diet. On the flip side, based on findings from the New Zealand Health Survey, the Ministry of Health reports that in the year to June 2025, just 4.2% of adults aged 15+ met their recommended daily fruit and vegetable intake.

It’s worth bearing in mind that UPF covers a broad range of processed foods and not all UPFs lead to poor health outcomes. Many, such as wholemeal and seeded bread, baked beans, fortified plant milks, yogurts, wholegrain breakfast cereals, and hummus provide essential nutrients such as fiber, protein, vitamins, and minerals. Some public health nutrition scientists prefer to focus on the use of industrial-trans fats, sugar content and salt content of packaged foods.

The Lancet papers are evidence that much of the food we eat leads to poorer health outcomes for consumers. These adverse costs (or externalities) are partly borne by the health system in terms of obesity treatments (I have already noted that obesity costs the health system $2 billion a year) and treatments for other diet-related conditions such as cardiovascular disease. And with a health system stretched to its limits, treating patients with obesity and other diet related conditions means less resources can be devoted to patients with other conditions.

Weight loss medication could reduce the overall healthcare cost, and shift the cost to Pharmac, but the health system, health insurers and policy holders, and ultimately the New Zealand taxpayer still bear the cost.

Costs are also borne by the consumers themselves in terms of lower quality of life and possibly lower earnings if poorer health outcomes affect people’s ability to work. This is where the waters get muddy. Personal choice and individual responsibility do play a role here. Consumers can choose to eat healthier food. But choices are influenced by environment and there is evidence that UPF content, packaging, advertising, product placement, and price are all designed to encourage consumption of UPFs at the expense of healthier food. In this line of thinking, UPF manufacturers bear at least partial responsibility for the poorer health outcomes their products contribute to. Yet they carry none of the resulting costs - those fall on the health system, the economy (in terms of lower productivity), and consumers themselves.

And the costs are not evenly spread. The OECD reports that obesity rates correlate with socio‑economic gradients, placing lower-income individuals at higher risk – partly due to their exposure to environments that encourage consumption of energy-dense foods, trans-fats and saturated fats, and sedentary lifestyles. So, costs are being disproportionately borne by people on lower incomes and, given how New Zealand’s obesity rates vary across ethnic groups, Pacific People and Māori are bearing these externalities most of all.

In my view, these externalities need to be addressed at the source. Food companies need to be regulated either to reduce production of foods that lead to poor health outcomes, or at least bear some of the costs of the poorer health outcomes that result.

Poor diets are often instilled in childhood. We need to protect our kids, not wait until they reach adulthood before we give them a medication to address their poor diets. A paper associated with The Lancet series states that taste preferences are formed in early childhood, and repeated exposure to UPFs conditions lifelong preferences for sweet, salty, and artificially flavoured foods. The authors also refer to research by UNICEF (United Nations Children’s Fund) which finds emerging evidence linking UPF consumption to all forms of malnutrition, metabolic alterations, and mental health concerns in children. Furthermore, children's developing cognitive abilities make them particularly vulnerable to the marketing of UPFs, especially when marketing strategies are deliberately tailored to appeal to them and exploit their reduced ability to recognise persuasive intent.

There is evidence that the majority of patients stop using GLP-1 medications after a year, usually after weight loss has occurred, and that once GLP-1 therapy is discontinued, most patients experience rapid weight regain.

These patients are being treated, then allowed back out into a food environment where food content, packaging, advertising, product placement, and price are all designed to encourage consumption of UPFs. As The Lancet papers concluded, relying on behaviour change by individuals is insufficient. No wonder these patients regained weight.

One of the underpinning issues with the current food environment is that consumers often aren’t fully aware of the health implications of the food they are consuming. An information asymmetry exists between the food producer and consumer.

The New Zealand Government is in the process of addressing this asymmetry with front-of-package Health Star Ratings (HSR) for food. Ratings are currently voluntary, but with uptake slow to date, ministers have requested Food Standards Australia New Zealand (FSANZ) to prepare a proposal on mandating the HSR system.

The researchers that contributed to the three papers published in The Lancet in 2025 concluded that the rise in UPFs is driven by global corporations that employ sophisticated political tactics to protect and maximise their profits. Education and relying on behaviour change by individuals is insufficient, they say. Deteriorating diets are an urgent public health threat that requires coordinated policies and advocacy to regulate and reduce UPFs and improve access to fresh and minimally processed foods.

Professor Swinburn, concludes that “In New Zealand we really need policies to create healthier food environments if we want to make a difference to our increasing rates of obesity, diabetes, and mental health problems.”

Proposals for regulation range from improving consumer information, restrictions on advertising, taxing foods based on their content, caps or outright bans on some ingredients, and reducing the political power of food corporations.

New Zealand’s Health Star Rating proposal is similar to Chile's 2016 Law of Food Labelling and Advertising which included mandatory warning labels, along with child-marketing restrictions and school sales bans of all foods and beverages containing added sugars, sodium, or saturated fats that exceed set nutrient or calorie thresholds. A before-and-after study found that the law resulted in a significant fall in consumption of high-sugar/salt/saturated fat/calorie drinks.

The UK’s Soft Drinks Industry Levy was implemented in April 2018. Industries manufacturing or importing sugar-sweetened beverages in the United Kingdom were taxed according to the sugar content of their drinks.

An evaluation showed that the Soft Drinks Industry Levy incentivised a reduction in sugar purchased in soft drinks and in food and drinks overall, reductions in obesity among some groups, reductions in hospital admissions for carious tooth extractions in children and adolescents, and did not have a lasting negative impact on the economic performance of soft drinks companies. Modelling estimated that there will be a net monetary benefit to the health sector, with a negligible impact on the UK’s GDP. The evaluation concluded that the Soft Drinks Industry Levy represented good value for money when balancing the overall health benefits against the economic impacts.

However, the jury is still out on the effectiveness of a sugar tax in New Zealand. A 2017 working paper by The Treasury looked at the potential implications of a food tax in New Zealand, and found that a sugar tax would be regressive at the general population level and that there is a risk of consumers substituting unhealthy but non-taxed products for taxed products, negating any potential health improvements from a tax. Other research has modelled the effects of a combined food-tax-and-healthy-food-subsidy policy and found it could improve diets and reduce mortality from diet-related disease in New Zealand. Using food tax revenue to subsidise more healthy food could also mitigate the regressive effects of such a tax. Revenue from food taxes could also be funnelled into the health budget to address treatments for dietary-related conditions.

In 2019, the European Union placed a cap on trans-fats in food - 2g of industrially-produced trans fats per 100g of fat. In 2022 it banned Titanium dioxide (E171) and, while potassium bromate, brominated vegetable oil, and propylparaben have not been outright banned in the EU, they've never been granted authorisation under the EU's positive-list additive system. Approval is required before an additive can be used in food. Denmark banned industrial trans fats nationally back in 2003/04. A modelling study found the ban accounted for around 11% of Denmark's overall decline in coronary heart disease deaths between 1991 and 2007.

One of three papers published in The Lancet addresses ways to counter corporate power in nations’ political processes. Their recommendations include Governments and political parties being transparent about which corporations they meet and political donations they receive, and cooling off periods for people working in regulatory bodies before they can be employed in the sectors they regulate, and vice versa.

In the run up to this year’s General Election, NZ's political conversation about the food sector has been almost entirely about affordability and competition, not about regulation of food production or advertising. The kinds of regulations enacted overseas might seem overbearing to many New Zealanders. It’s much easier to place the blame for poor health outcomes on the individual consumer and their food choices. But right now, New Zealanders don’t even have a choice about food regulation.

I’d like to see one of the major parties put forward an ambitious plan for food regulation, sell it to New Zealanders as a way to improve people’s lives, save lives, and reduce health spending, and have a healthy debate about it in the media. So when the time comes to cast votes, New Zealanders will be able to choose for themselves how much regulation they want.