Scientists in New Zealand created a computer tool to find the best diets that are good for your body, good for your wallet, and good for the environment. They discovered something interesting: you can cut food costs or pollution by huge amounts, but people won’t want to eat those diets because they’re too boring and repetitive. The good news? You can still reduce pollution by 10-30% and save money while eating foods you actually enjoy. This research shows that the most sustainable diets don’t have to feel like punishment—they just need to be realistic about what people will actually eat.

The Quick Take

  • What they studied: Can we create healthy diets that are affordable, reduce pollution from food production, and that people will actually want to eat?
  • Who participated: The study used computer modeling to analyze what adult men and women in New Zealand typically eat, then tested different diet scenarios to find the best balance between health, cost, and environmental impact.
  • Key finding: Diets that cut pollution or costs by 80% are possible but require eating the same boring foods repeatedly, making them unrealistic. However, diets that cut pollution by 10-30% while staying affordable and close to normal eating patterns are both achievable and practical.
  • What it means for you: You don’t need to make extreme changes to help the environment and save money on food. Small, realistic adjustments to what you eat can make a real difference without feeling like you’re sacrificing taste or variety.

The Research Details

Researchers created a special computer program called the iOTA Model that works like a puzzle-solver for diets. It uses mathematical programming to find the best combinations of foods that meet three goals at once: giving your body all the nutrients it needs, costing as little as possible, and producing the least pollution from food production. The program was built using real food and nutrition information specific to New Zealand, including details about how well your body can actually absorb nutrients from different foods.

The researchers tested eight different diet scenarios for both men and women aged 19-30 years. Each scenario prioritized different goals—some focused mainly on reducing pollution, others on cutting costs, and some tried to balance everything while staying close to what people normally eat. They compared all these scenarios to what New Zealanders actually eat today (called the baseline diet).

What makes this tool special is that it’s available for free online, so other scientists and researchers can use it to study sustainable eating in their own countries. The model considers real-world factors like how much food costs, how much pollution different foods create, and whether the foods are actually available and acceptable to eat.

Most research about sustainable eating focuses only on the environment, ignoring whether people can afford the food or will actually eat it. This study is important because it looks at all three factors together. It also addresses a real problem in New Zealand where many people struggle with food insecurity—meaning they don’t always have enough money for food. Understanding how to make sustainable diets that are also affordable and appealing helps solve real-world problems, not just environmental ones.

This research uses a sophisticated computer modeling approach, which is reliable for testing many diet combinations quickly. However, the study doesn’t involve actual people eating these diets—it’s based on calculations and existing data. The tool was built specifically for New Zealand, so results may differ in other countries with different food availability and eating habits. The strength of this research is that it considers multiple real-world factors together rather than looking at them separately.

What the Results Show

The most striking finding was that extreme sustainability goals create unrealistic diets. When researchers asked the computer to find diets that cut pollution by 80% or reduce costs by 80%, it was mathematically possible while still meeting all nutritional needs. However, these diets required eating very limited varieties of foods repeatedly—imagine eating the same five foods every single day. People wouldn’t accept these diets in real life because they’re boring and don’t match how people actually like to eat.

The breakthrough finding was that more modest goals work much better in practice. When the computer was asked to find diets that stayed close to what people normally eat while still improving sustainability, it found realistic options. For women aged 19-30, the model found diets that reduced food-related pollution by 10% while keeping costs the same or lower than current eating patterns. For men in the same age group, it achieved a 30% reduction in pollution while maintaining affordability and staying close to normal eating habits.

These realistic diets included a good variety of foods that people actually enjoy eating, making them something people could stick with long-term. The key insight is that you don’t need to make extreme changes—small, practical adjustments work better than trying to completely overhaul your diet.

The research revealed important differences between men and women. Men’s typical diets in New Zealand produced more pollution than women’s diets, which is why men could achieve greater pollution reductions (30%) while staying realistic. This suggests that men might have more room to make sustainable changes without sacrificing variety or enjoyment. The study also showed that food costs and environmental impact don’t always go together—sometimes the cheapest foods are also the most polluting, and sometimes they’re not, depending on the specific foods involved.

Previous research has shown that sustainable diets are possible, but much of that work ignored whether people would actually eat them or could afford them. This study builds on that by adding the crucial element of ‘acceptability’—whether the diet matches what people actually enjoy eating. It also adds to growing evidence that extreme dietary changes often fail because they’re too difficult to maintain. The finding that modest changes (10-30% improvement) are more realistic than extreme ones (80% improvement) aligns with what we know about behavior change in general.

This study used computer modeling rather than testing actual diets with real people, so we don’t know for certain how people would respond to these diets in practice. The research focused on New Zealand, so the results may not apply to other countries with different foods, prices, and eating habits. The study looked at adults aged 19-30 years, so we don’t know if the same patterns would apply to children, teenagers, or older adults. Additionally, the study didn’t account for cultural food preferences or social factors that influence eating choices beyond just variety and cost.

The Bottom Line

Based on this research, aim for modest improvements rather than extreme dietary overhauls. Try to reduce your food-related environmental impact by 10-30% through small changes like eating slightly less meat, choosing more plant-based foods, or buying foods that are in season. These changes can often save money while maintaining the variety and enjoyment in your diet. Confidence level: Moderate to High—this is based on solid modeling, though real-world testing would strengthen the evidence.

This research matters most for people interested in eating more sustainably without feeling deprived, people on tight food budgets, and policymakers in New Zealand and similar countries trying to improve food system sustainability. It’s particularly relevant for people who’ve tried extreme diets and found them unsustainable. It’s less directly applicable to people in countries with very different food systems, though the general principle—that realistic changes work better than extreme ones—likely applies everywhere.

You could see benefits in your food budget within a few weeks of making small dietary changes. Environmental benefits accumulate over time as more people make similar changes. Health benefits from eating more plant-based foods typically appear over weeks to months. The key is that these realistic changes are sustainable long-term, unlike extreme diets that most people abandon.

Want to Apply This Research?

  • Track your weekly food spending and estimate the environmental impact of your meals using a simple scoring system (assign points based on whether foods are plant-based, seasonal, or locally produced). Compare your baseline spending and impact score to your score after making small dietary changes.
  • Start by identifying one meal per week to modify toward sustainability—for example, replacing one beef meal with a plant-based alternative, or choosing seasonal vegetables instead of imported ones. Use the app to log this change and track both your spending and estimated environmental impact over 4-8 weeks.
  • Create a monthly dashboard showing your food costs, variety of foods eaten (count unique foods per week), and estimated environmental impact. Set a goal to reduce impact by 10-15% over three months while maintaining food variety and staying within budget. Review monthly to see if your changes are sustainable and adjust as needed.

This research is based on computer modeling and has not been tested with actual people following these diets. The findings are specific to New Zealand and may not apply to other regions with different food systems, availability, and costs. Before making significant dietary changes, especially if you have health conditions, food allergies, or are pregnant or breastfeeding, consult with a healthcare provider or registered dietitian. This research suggests what’s theoretically possible, not what’s medically necessary or appropriate for every individual. The environmental and cost benefits described are estimates based on modeling and may vary based on your specific location, food sources, and shopping habits.