How our food system fuels both obesity and climate change—and how to fix it

Obesity, one of the world’s most important health challenges, shares a common driver with climate change. Our food environment is driving both of these “co-crises”: diets dominated by energy-dense, low-fiber, ultra-processed foods (UPFs) and emissions-intensive livestock push both calorie intake and greenhouse gases upwards. A shift toward minimally processed, plant-rich food can improve health and cut emissions.

In their Frontiers in Science article, Behrens et al. review recent developments in our understanding of obesity and its links to climate change and environmental damage. While recognizing the importance of new obesity treatments, they argue for coordinated, science-led action to address the root cause of obesity—our current food systems.

This explainer summarizes the article’s main points.

How serious is the global obesity epidemic?

Over 2.6 billion people—38% of the world’s population—are living with excess weight or obesity. This is projected to reach 50% by 2035, with the greatest increases predicted in children and adolescents.

This is a major concern because obesity is a key risk factor for many conditions, including cardiovascular disease, type 2 diabetes, and cancer. As well as high rates of mortality, the global rise in obesity is predicted to confer enormous costs and an unsustainable burden on healthcare systems.

Are drugs and surgery the answer?

Bariatric surgery, as well as anti-obesity medications known as GLP-1 receptor agonists, offer important therapeutic advances that can transform the lives of people living with obesity.

However, scaling them to every adult and child with overweight and obesity would be potentially risky and unaffordable. The authors conclude that relying on treatment alone is unsustainable, and that prevention through healthier food environments is essential.

What are UPFs and why do they matter?

Obesity is a complex condition with multiple contributing causes. There is now extensive evidence that the obesity epidemic is being driven primarily by the transformation of our food environment toward diets dominated by energy-dense UPFs.

UPFs are industrial formulations made largely from refined ingredients and additives. The authors say UPFs act through multiple addictive and “obesogenic” pathways that promote overeating and weight gain.

However, not all UPFs have the same impact. Emerging evidence suggests that processed meat and low-fiber, energy-dense UPFs are associated with poorer outcomes than less calorific, plant-rich UPFs. The authors argue that more nuanced classifications would help policy and clinical guidance.

What is the link between obesity and climate change?

Current food environments that promote weight gain also contribute significantly to climate change.

Animal-based foods—especially meat and dairy—dominate the environmental footprint of diets. Production systems involving ruminant livestock (like cattle) release large amounts of methane, a potent greenhouse gas, and put pressure on land and water use. The authors highlight evidence that producing 100 g of protein from beef emits around 50 kg CO₂-eq, versus just 0.84 kg from beans for the same amount of protein.

Large studies have shown strong co-benefits for human and planetary health from dietary shifts toward more plant-based foods (e.g., EAT-Lancet-aligned diets) and less ruminant meat. Studies link these diets to lower risks of death and major diseases as well as big cuts in greenhouse gas emissions. This “double benefit” could also free up land for nature recovery, which would boost carbon storage, biodiversity, flood protection, and access to green spaces.

What are the wider social and environmental stakes?

The same food practices worsening obesity can also entrench poverty and degrade land—especially where transnational corporations are allowed to reshape local farming into large plantations with weak regulatory oversight. Shifting diets and production can thus support health, climate goals, and fairer livelihoods.

What changes do the authors recommend?

The authors call for evidence-based food system reforms that reduce the over-consumption of energy-dense UPFs and animal-sourced foods, especially from ruminants. To make that shift possible, they outline priority actions:

• change the cost of unhealthy foods to reflect their true cost to society and our environment

• tax unhealthy foods, directing revenue to public health programs

• curb persuasive marketing, especially to children

• improve front-of-pack labeling so healthy choices are easier

• design healthier living environments—from school meals to urban planning

• educate the public and professionals with consistent, evidence-based messages.

What are the barriers and how should they be overcome?

The authors stress that solutions exist but remain underused due to commercial interests and a lack of political will.

Removing market distortions to reflect the true cost of unhealthy food, as well as allowing consumers to make well-informed choices, will require system-level solutions involving medical and public health communities, policymakers, industrial leaders, institutions, educators, and the public. The authors say that these stakeholders working together can result in collaborative policy shifts to change behaviors and food systems.

They recommend that new economic models, market demand shifts, and technological innovation should all be harnessed to overcome economic and political barriers. They also argue that transitioning to non-obesogenic and sustainable food systems would likely also be very economically advantageous to societies.