Global Warming Obesity, Climate Change Linked with Global Food Systems

The authors of a recent paper have revealed that changing the consumption-driven nature of our food systems would significantly benefit public health and the climate.

Bristol/UK – The paper, ‘Obesity and climate change: co-crises with common solutions’, published in Frontiers in Science recently is based on a review of recent evidence from epidemiology, endocrinology, psychology, public health, nutrition and food systems, economics and environmental science.

According to the evidence, half the world’s population is projected to be overweight or obese, diseases which increase the risk of serious conditions such as heart disease and cancer. Meanwhile, global heating now kills one person every minute around the world, accounting for around 546,000 deaths per year over the period 2012-2021, up 63 % from the 1990s.

Food production is responsible for between a quarter and a third of total greenhouse gas emissions, and is the leading cause of land clearance, which drives deforestation and biodiversity loss.

Among the recommendations proposed by the authors are subsidies for healthy foods, taxes and warning labels for particularly unhealthy foods, and restrictions on aggressive marketing of high-calorie, low-fibre products, particularly in low-income communities and to children.

One of the authors is Jeff Holly, Professor of Clinical Science at The University of Bristol. He said: “While obesity is a complex disease driven by many interacting factors; the primary driver is the consumption-driven transformation of the food system over the last 40 years. Unlike weight loss drugs or surgery, addressing this driver will help humans and planet alike.”

The authors note that even if fossil fuel emissions ended today, current food systems alone could still push global temperatures beyond the 2°C threshold. Ruminant meat production is particularly impactful, with beef generating far greater emissions than plant-based sources.

“We can’t solve the climate crisis without transforming what we eat and how we produce it,” said first author Professor Paul Behrens from University of Oxford, and Leiden University, the Netherlands. “To tackle the climate crisis, we must tackle food systems that push up emissions and push us toward energy-dense and highly processed diets full of animal products.”

The review calls for food system reforms to replace energy-dense UPFs with unprocessed foods and reduce animal-sourced foods. They also call for a better classification system for UPFs to enhance clarity—highlighting that not all UPFs are made equal. For example, processed meat, and low-fiber, energy-dense UPFs have poorer health and environmental outcomes than less energy-dense, high-fiber, plant-rich UPFs.

The authors note that while weight-loss drugs and bariatric surgery provide important options for individuals with obesity, they fail to address the wider environment that affects whole populations and ecosystems. Concerns also remain over long-term affordability, safety, and sustained global access to these treatments, particularly as obesity increasingly affects younger and lower-income populations.

“The rise of obesity and non-communicable diseases in children and youth is alarming,” said co-author Professor Katherine Samaras from St Vincent's Hospital, the Garvan Institute of Medical Research, and University of New South Wales, all in Australia. “For adults and children alike, individual willpower is no match for aggressive marketing campaigns.

“Although treatments such as medicines and surgeries offer important therapeutic options for individuals, they won't substitute for tackling our unhealthy, unsustainable food and living environments.”

Preventing weight gain through healthier food environments would be “far cheaper and less harmful,” the authors note, than adapting to the consequences of both obesity and climate change, or treating individuals instead of changing systems. Obesity-related expenses cost over 2 % of global GDP in 2019. These are projected to exceed 4 trillion dollars by 2035 if trends continue.

The authors stress that national strategies to address obesity have so far focused on personal responsibility, based on the perception of it being a lifestyle issue. This, they note, has failed to slow the rise in obesity, and they argue that coordinated science-led reform of food environments can address both the root cause of obesity and environmental harms.

“Treating individuals—instead of the system that’s making them sick—perpetuates the misguided idea that obesity stems from a lack of willpower in individuals,” added Professor Holly. “To reduce the food system’s health and climate burden, governments must first recognize that both climate change and obesity are symptoms of profit-driven, systemic problems—and address the root.”

The authors note that, although multiple lines of evidence link UPFs, obesity, and climate impacts, the underlying pathways are complex, and several proposed mechanisms remain insufficiently understood. They emphasize that further research is needed to clarify causal processes and strengthen the evidence base.

“We risk undoing the gains from healthcare innovations and economic growth if we don’t urgently tackle these twin crises,” added Professor Holly.

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