Tackling unsustainable food systems is urgent for both health and climate, according to new research.
An international team of researchers has published a new paper in Frontiers in Science reviewing evidence that both obesity and environmental harms result from a profit-led food system that encourages high intake and poor health. The authors say our food environment promotes high-calorie, low-fibre ultra-processed foods (UPFs) — the most calorific of which encourage weight gain. Those same production systems, especially involving animals, release large amounts of greenhouse gases and put pressure on land and water.
The comprehensive review, led by Prof Jeff Holly, of the University of Bristol, says addressing the food environment can deliver double benefits for health and climate.
The authors recommend using 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.
They also counter the perception that weight-loss drugs are a panacea for obesity, as they do not address the systemic drivers that also harm the climate.
"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," Prof Holly says. "Unlike weight-loss drugs or surgery, addressing this driver will help humans and planet alike."
By 2035, half the world’s population is projected to be overweight or living with obesity — diseases that 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 about 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.
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," another of the paper’s authors, Prof Paul Behrens, says. "To tackle the climate crisis, we must tackle food systems that push up emissions and push us towards 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 — highlighting that not all UPFs are made equal. For example, processed meat, and low-fibre, energy-dense UPFs have poorer health and environmental outcomes than less energy-dense, high-fibre, plant-rich UPFs.
Obesity increases the risk of premature death and is a major driver of non-communicable diseases. For example, a recent study in China found that half of newly diagnosed cancers were obesity-related, with an alarming rise among younger generations.
The health impacts together make obesity one of the largest contributors to global ill-health beyond its economic burden.
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.
"The rise of obesity and non-communicable diseases in children and youth is alarming," co-author Prof Katherine Samaras says. "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."
The researchers recommend:
• taxes on energy-dense UPFs and sugar-sweetened beverages
• subsidies to make minimally processed, healthy foods more affordable, funded by taxes on unhealthy food
• improving public awareness of the true cost of food via educating the public and healthcare professionals
• tobacco-style front-of-pack labelling and restrictions on marketing unhealthy foods to children
• policies that support healthy school meals and local food sourcing
• shifting diets towards minimally processed, fibre-rich plant foods and fewer animal products.
"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," Prof Holly says. "To reduce the food system’s health and climate burden, governments must first recognise that both climate change and obesity are symptoms of profit-driven, systemic problems — and address the root."
