1429. How to Eat Healthy Within the Earth's Boundaries

In an editorial in Nature, Dr. Johan Rockström, known as the proponent of the "Planetary Boundaries" concept, argued that a change in dietary habits, supported by bold policies, is essential for a sustainable planet.

The Planetary Boundaries framework identifies nine biophysical thresholds that must be met to avoid destabilizing the Earth. Dr. Rockström emphasizes that from a global perspective, what we eat is not simply a lifestyle choice but a systems-wide issue that affects the health of humanity and the planet.

Currently, food production and consumption account for approximately 30% of global greenhouse gas emissions, and agriculture accounts for approximately 70% of the world's annual freshwater use. Agriculture is also a major driver of nutrient pollution and biodiversity loss.

Current diets are damaging human health. Each year, approximately 15 million adults die prematurely due to unhealthy diets. This death toll exceeds the annual deaths caused by global air pollution. Currently, only 1% of the world's population lives in a "safe and just space" where people's rights and food needs are met within the planet's limits.

Last October, the EAT-Lancet 2025 Commission, which Dr. Rockström was involved in, proposed a revised Planetary Health Diet (PHD). This diet is rich in fruits, vegetables, nuts, legumes, and whole grains, and recommends consuming approximately one serving of lean meat and two moderate servings of poultry and seafood per week. The PHD is highly flexible, and many traditional cuisines, including those from the Mediterranean, South Asia, East Asia, Africa, and Latin America, already follow its principles. This healthy, plant-rich diet helps prevent diseases such as heart disease, diabetes, and some cancers. Protein provides all essential nutrients and contributes approximately 14% of daily energy.

However, most people's diets currently deviate significantly from this. In many countries, people consume too many animal products and not enough vegetables, fruits, legumes, and nuts. Furthermore, diets that rely heavily on ultra-processed foods are increasingly ingrained in cultures around the world.

The EAT-Lancet Commission examined whether a population of approximately 10 billion people can be fed within the planet's limits by 2050. The results are grim: healthy diets, reduced food waste, and the adoption of sustainable production practices such as conservation tillage to maintain soil fertility and sequester carbon could reduce global greenhouse gas emissions by 20% by 2050. However, without dietary changes, emissions will increase by 33%.

Dr. Rockström called for a variety of policies, including subsidies and incentives for plant-based agriculture, taxes or caps on emission-intensive meat production, investments in crop-diversified supply chains, and public procurement standards that prioritize healthy and sustainable food. This transformation will be costly, requiring an estimated annual investment of up to US$500 billion. However, the net benefits (approximately US$5 trillion to US$10 trillion) are expected to far outweigh these costs, including reduced healthcare costs due to healthier diets, reduced climate damage, and reduced environmental degradation.

Dr. Rockström argued that any credible path to limiting global warming to 1.5°C above pre-industrial levels presupposes a transformation of the food system that shifts agriculture from a major greenhouse gas emitter to a net sink. He called for a green food revolution rooted in science and justice.

Contributor: IIYAMA Miyuki, Information Program