Research shows that an ovo-lacto-vegetarian diet—which includes eggs and dairy but excludes meat—can reduce greenhouse gas emissions by 58% and land use by 61% while meeting nearly all nutritional needs and potentially preventing 41% of diet-related diseases. According to Gram Research analysis, this plant-based approach requires only modest changes from typical eating patterns, making it realistic for people to adopt without sacrificing health or nutrition.
A new study from Austria shows that switching to an ovo-lacto-vegetarian diet (which includes eggs and dairy but no meat) can dramatically reduce your environmental impact while keeping you healthy. Researchers used computer modeling to design a plant-based diet that cuts greenhouse gas emissions by 58% and land use by 61% compared to what typical Austrian adults eat. The diet still provides all the nutrients your body needs, except for two omega-3 fatty acids found mainly in fish. This research suggests that eating more vegetables, fruits, grains, and legumes while eating less meat and dairy is possible without sacrificing nutrition or taste.
Key Statistics
A 2026 mathematical modeling study published in Frontiers in Nutrition found that an ovo-lacto-vegetarian diet reduced greenhouse gas emissions by 58% and land use by 61% compared to typical Austrian adult diets while meeting nearly all nutritional requirements.
Research reviewed by Gram shows that the optimized plant-based diet could prevent or reduce 41% of disability-adjusted life years related to diet-related diseases in the Austrian population compared to current eating patterns.
According to the 2026 study, plant-based foods provided 65% of total protein in the optimized vegetarian diet, with animal-based foods contributing only 21% of daily energy intake compared to 29% in typical diets.
The optimized ovo-lacto-vegetarian diet resulted in greenhouse gas emissions of 2.5 kg CO2-equivalent per day and land use of 2.9 square meters per day, representing reductions of 58% and 61% respectively from observed dietary patterns.
The Quick Take
- What they studied: Can scientists design a plant-based diet that is healthy for people, good for the environment, and doesn’t require huge changes to what we normally eat?
- Who participated: The study used data from typical eating patterns of Austrian adults as a baseline, then used computer modeling to create an optimized plant-based diet plan.
- Key finding: An ovo-lacto-vegetarian diet (with eggs and dairy) can reduce greenhouse gas emissions by 58% and land use by 61% while meeting nearly all nutritional needs and reducing disease burden by 41%.
- What it means for you: Eating more plants and less meat doesn’t have to mean giving up all animal products or eating completely different foods. Small shifts toward more vegetables, legumes, and grains can help the planet while keeping you healthy. You may need to supplement omega-3 fatty acids from fish sources or supplements.
The Research Details
Researchers used mathematical computer modeling to design the perfect plant-based diet. They started with what typical Austrian adults actually eat, then used a computer program to gradually swap out meat and dairy for plant-based foods while keeping the diet as similar as possible to what people normally eat. The goal was to create a diet that met all nutritional requirements, reduced environmental impact by at least 45%, and didn’t require people to make huge changes to their eating habits.
The researchers checked the optimized diet against official nutritional guidelines to make sure it provided enough vitamins, minerals, and other nutrients. They also calculated how much greenhouse gas (like carbon dioxide) the diet would produce and how much land it would need. Finally, they estimated how many diseases and health problems the new diet could prevent compared to current eating patterns.
This approach is important because it shows that healthy eating and environmental protection don’t have to be in conflict. By using computer modeling, scientists can design realistic diets that people might actually follow, rather than suggesting extreme changes that most people won’t stick with. This method can be used in other countries to create dietary guidelines that work for their specific foods, cultures, and environmental needs.
This study used a systematic mathematical approach, which is reliable for modeling. However, the study is based on Austrian eating patterns and may not apply exactly to other countries with different foods and cultures. The research didn’t test whether real people would actually follow this diet or how it would affect their health over time. The study also identified that the diet falls short on two omega-3 fatty acids (DHA and EPA) found mainly in fish, which would need to be addressed through supplements or fortified foods.
What the Results Show
The optimized ovo-lacto-vegetarian diet successfully met nearly all nutritional requirements while dramatically reducing environmental impact. Greenhouse gas emissions dropped from typical levels to 2.5 kg of carbon dioxide equivalent per day—a 58% reduction. Land use fell from typical levels to 2.9 square meters per day—a 61% reduction. These reductions exceeded the study’s goal of 45% improvement.
The diet achieved these environmental gains by shifting the source of protein and calories. In the typical Austrian diet, animal-based foods provided 29% of daily calories. In the optimized diet, this dropped to 21%. Meanwhile, plant-based foods provided 65% of total protein in the optimized diet, up from much lower levels in the typical diet. The diet emphasized vegetables, fruits, whole grains, and legumes while keeping only small amounts of eggs and dairy.
Beyond environmental benefits, the optimized diet showed potential health improvements. Compared to the current diet-related disease burden in Austria, the new diet could prevent or reduce 41% of disability-adjusted life years (DALYs)—a measure that combines years lost to disease and disability. This suggests the plant-based diet could prevent significant health problems.
The study identified that the optimized diet fell short on two omega-3 fatty acids called docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are primarily found in fish and seafood. This means people following this diet would need to either eat small amounts of fish, take supplements, or consume foods fortified with these nutrients. The research also showed that the optimized diet required only modest changes from typical eating patterns, making it more realistic for people to adopt than more extreme plant-based approaches.
This research builds on growing evidence that plant-based diets can be both healthy and environmentally sustainable. Previous studies have shown that reducing meat consumption lowers environmental impact, but this study goes further by using mathematical modeling to create a specific, nutritionally complete diet plan. The finding that a diet with some animal products (eggs and dairy) can achieve major environmental benefits aligns with other research suggesting that flexitarian or vegetarian approaches may be more sustainable than strict vegan diets for many populations.
The study used computer modeling rather than testing the diet with real people, so we don’t know if people would actually follow it or how it would affect their health in practice. The research is based on Austrian food availability and eating patterns, so the specific recommendations may not work as well in other countries with different foods and cultures. The study also couldn’t address the DHA and EPA shortfall within the plant-based framework, requiring supplementation. Additionally, the study didn’t account for factors like food cost, food preferences, or cultural food traditions that influence whether people actually change their diets.
The Bottom Line
According to Gram Research analysis, eating an ovo-lacto-vegetarian diet (including eggs and dairy but not meat) can significantly reduce your environmental footprint while maintaining good health. Focus on eating more vegetables, fruits, whole grains, and legumes. Keep eggs and dairy products in small amounts. Consider taking an omega-3 supplement or eating small amounts of fish to get DHA and EPA. This approach is supported by strong evidence from nutritional modeling, though real-world testing would strengthen the findings.
This research is relevant for anyone interested in eating in a way that’s better for the environment without sacrificing health. It’s particularly useful for people considering vegetarianism or looking to reduce meat consumption. Policymakers developing national dietary guidelines should pay attention to this research. People with specific health conditions, allergies, or cultural food requirements should consult with a healthcare provider or dietitian before making major dietary changes.
Environmental benefits would begin immediately—every meal following this diet reduces your carbon footprint. Health benefits like reduced disease risk typically develop over months to years of consistent eating patterns. You might notice increased energy or better digestion within weeks, but major health improvements usually take 3-6 months or longer to become apparent.
Frequently Asked Questions
Can a vegetarian diet that includes eggs and dairy be as healthy as eating meat?
An ovo-lacto-vegetarian diet can meet nearly all nutritional needs and may prevent 41% of diet-related diseases compared to typical diets. You’ll need to supplement omega-3 fatty acids (DHA and EPA) found mainly in fish, but otherwise the diet provides complete nutrition through legumes, grains, vegetables, eggs, and dairy.
How much can I reduce my environmental impact by eating less meat?
Switching to an ovo-lacto-vegetarian diet can reduce your greenhouse gas emissions by 58% and land use by 61%. These reductions come primarily from replacing meat with plant-based proteins like legumes, which require far fewer resources to produce than animal products.
Do I have to give up all animal products to help the environment?
No. Research shows that keeping small amounts of eggs and dairy while eliminating meat can achieve major environmental benefits—58% reduction in emissions—while remaining nutritionally complete. This approach is more realistic for many people than strict veganism.
What foods should I eat more of on a plant-based diet?
Focus on vegetables, fruits, whole grains, and legumes (beans, lentils, chickpeas). These foods should make up about 79% of your daily calories. Keep eggs and dairy products in small amounts, and consider adding plant-based meat alternatives to support the transition.
How long does it take to see health benefits from changing to a vegetarian diet?
Environmental benefits start immediately with each meal. You might notice improved energy or digestion within weeks. Significant health benefits like reduced disease risk typically develop over 3-6 months or longer of consistent eating patterns.
Want to Apply This Research?
- Track your daily servings of legumes, vegetables, and whole grains compared to meat and dairy. Aim to increase plant-based foods to 65% of your protein sources and reduce animal-based foods to 21% of your daily calories.
- Start by replacing one meat-based meal per day with a legume-based meal (like lentil soup, bean chili, or chickpea curry). Add one new plant-based recipe to your weekly rotation each week. Keep eggs and dairy as condiments or small additions rather than main ingredients.
- Weekly check-ins on plant-based meal frequency and legume servings. Monthly tracking of how you feel (energy levels, digestion, mood). Quarterly assessment of your environmental impact using a carbon footprint calculator to see your progress.
This research presents mathematical modeling of a theoretical diet and has not been tested with real people over time. Individual nutritional needs vary based on age, sex, activity level, health conditions, and medications. Before making significant dietary changes, especially if you have health conditions, take medications, or have food allergies, consult with a healthcare provider or registered dietitian. The study identifies that this diet may be deficient in DHA and EPA omega-3 fatty acids, which would require supplementation or consumption of fortified foods. This article is for educational purposes and should not be considered medical advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.