People consume more added sugar through products like soft drinks and frozen desserts during periods of rising temperature and heatwaves, according to a new study involving the University of Southampton.
A team of researchers analysed 15 years of shopping data and found sugar intake increases with temperature.
The effects were most noticeable between 12°C and 30°C, and more common among people with lower incomes or education, the data showed.
The study, with Cardiff University, is among the first to identify a climate-diet-health connection against such a comprehensive dataset. The team's findings, published in the journal Nature Climate Change , emphasise the need to manage the health impacts of added sugar and find ways to adjust diets in a changing climate.
Co-corresponding author Dr Duo Chan from the University of Southampton, said: "Our study focuses on the US, but rising heat from climate change is a global challenge, with more severe consequences in arid areas and in colder regions where warming is most rapid."
First author Dr Pan He from Cardiff said: "While much research has focused on how climate change affects food production, we know far less about how it influences what people actually eat.
"Our study addresses that gap by examining how rising temperatures-especially in hot weather-may lead to increased consumption of added sugar, especially through products like sugary drinks and frozen desserts. This is a concern because excessive added sugar is linked to serious health issues like obesity, diabetes, and cardiovascular disease."
By projecting future sugar intake under warming climate scenarios, the paper highlights an emerging public health challenge that requires both mitigation and adaptation strategies, the researchers warn.
"What surprised us most was that the strongest increase in added sugar consumption occurred not during extreme heat, but within a relatively mild temperature range-between 12°C and 30°C," said Dr He. "This suggests that even moderate warming can significantly influence dietary behaviour, leading to increased consumption of sugar-sweetened beverages and frozen desserts."
The study is also motivated by growing evidence that climate impacts on diet can vary widely across income, education levels and different ethnic groups. The researchers found the greatest impact of this added sugar consumption in low-income and less-educated households, suggesting climate change may unintentionally worsen diet-related health risks and widen existing nutritional inequalities.
While the analysis focusses on US households, the researchers say their findings are also relevant to other high-income countries with similar dietary patterns.
"As the UK also experiences warming trends due to climate change, understanding how temperature affects food choices is crucial for anticipating public health challenges," warns Dr He.
"So even for policymakers here in Wales and the rest of the UK, our data underscores the need to incorporate dietary risk considerations into climate resilience planning, especially for vulnerable population groups."
