Global food system driving obesity and climate crisis, major review finds
The way food is produced, marketed and consumed in the UK and globally is driving both rising obesity rates and worsening climate change, according to a major scientific review that calls for urgent reform of the food system.
The review, published in Frontiers in Science, argues that the same factors encouraging unhealthy weight gain — particularly the widespread availability of cheap, ultra-processed foods and diets high in red meat — are also responsible for significant environmental harm.
More than one billion people worldwide are now living with obesity, according to the World Health Organization, with numbers projected to reach 1.3 billion by 2030. This is despite record levels of weight-loss medication use and bariatric surgery. Meanwhile, food production is responsible for around a quarter to a third of global greenhouse gas emissions.
“The food system drives both the obesity epidemic and environmental damage,” said Paul Behrens, British Academy Global Professor at the University of Oxford and lead author of the review.
Researchers describe obesity and climate change as “two sides of the same coin”, both shaped by food environments that prioritise highly processed, calorie-dense products which are heavily marketed and often cheaper than healthier options.
The review highlights the role of ultra-processed foods in excess calorie intake, while also drawing attention to the environmental impact of meat-heavy diets. Cattle farming produces methane, a powerful greenhouse gas, and contributes to deforestation in ecologically sensitive regions.
However, the authors stress that not all ultra-processed foods are equal. Some processed plant-based foods may be healthier and have a far lower environmental footprint than unprocessed meat.
While recognising that weight-loss drugs and bariatric surgery can be life-changing for individuals, the researchers warn that these approaches risk focusing on treatment rather than prevention.
“These are highly invasive and expensive responses to a problem that is largely driven by the food environment and the companies shaping it,” Behrens said.
The review also raises concerns about health inequalities. People on lower incomes are more likely to rely on cheaper, less nutritious foods and are less able to access costly medical treatments for obesity.
Instead, the authors point to population-wide policies that could improve health while also reducing environmental harm. These include taxes on sugary foods and drinks, clearer food labelling, tighter restrictions on the marketing of unhealthy foods to children, and redirecting agricultural subsidies away from the most polluting products.
Data from Europe suggest that around 82 per cent of food subsidies currently support foods that are among the most damaging to both health and the environment, including meat and dairy products.
The review also highlights the potential of public procurement where governments purchase food for schools, hospitals and other public institutions as a powerful tool for change. Making healthier, more sustainable meals the default in these settings could improve diets while supporting farmers to grow more sustainable crops.
Although the review focuses on systemic change, it acknowledges the role of individual choice.
“We shouldn’t place all the responsibility on individuals,” Behrens said. “But at the same time, people do make daily food choices, and those choices matter.”
The authors conclude that tackling obesity in the UK and globally will require reshaping the food system to make healthier, sustainable food the easy and affordable option for everyone.