Warmer temperatures tied to higher sugar purchases, study warns climate change could worsen obesity risk

A new international study published in Nature Climate Change finds that hotter weather is associated with higher household purchases of sugar, a pattern the authors say could amplify obesity and other diet-related health problems as the planet warms.

Researchers who compared U.S. household grocery-purchasing records from 2004 to 2019 with local meteorological data including temperature, humidity and wind speed report a clear relationship between daily temperature and sugar bought. Between about 12°C and 30°C (54°F and 86°F), the team found purchases contained, on average, 0.7 grams more sugar per day for each degree Celsius of warming.

The increase in sugar purchases was detectable at relatively mild temperatures and accelerated around 20°C, the authors write, becoming most rapid between roughly 24°C and 30°C. Sugar-related purchases continued to climb at temperatures above 30°C. Using climate projections, the study estimates that under a scenario in which global mean temperatures rise about 5°C above preindustrial levels by 2095, the average American could purchase an additional 2.99 grams of sugar per day as a result of temperature-driven changes in buying patterns.

Lead author Pan He of Cardiff University told the Daily Mail that two mechanisms likely drive the effect: higher temperatures increase metabolic rate and hydration needs, and people often choose sweetened beverages and frozen desserts to cool down. "If one is used to using sweetened beverages to hydrate themselves, then this would become the problem," Dr. He said. "One may use frozen food and drinks to physically cool down, and many of these products have added sugar, such as frozen yoghurt and ice cream."

Co-author Duo Chan of the University of Southampton said the work highlights a slower, dietary pathway by which rising temperatures could affect health. "So far, the health impact of climate change has been described mainly in terms of how extreme heat can cause heat stroke," he said. "On the other end of the spectrum, what we find is the slower, long-term influence of temperature change, acting through diet."

The study exploits a large, high-resolution retail dataset that links household-level purchases to local daily weather conditions across the United States. That approach allowed the researchers to isolate short-term relationships between temperature fluctuations and the sugar content of groceries bought by households over 15 years.

The authors report heterogeneity in the response: households with lower income and lower educational attainment increased sugar purchases more rapidly as temperatures rose, suggesting that climate-driven dietary shifts could exacerbate existing socioeconomic disparities in diet-related disease burdens.

The paper notes several caveats. The analysis measures purchases rather than direct individual consumption; not all purchased sugar products are consumed immediately or by the purchaser. The projection of additional daily sugar intake by 2095 uses a relatively high-end warming scenario (approximately 5°C of global mean warming above preindustrial levels), and outcomes would differ under lower-emission pathways.

Public-health researchers have previously documented direct heat-related harms such as heat stroke and cardiovascular stress. This study adds evidence for an indirect pathway linking moderate daily warming to changes in food and beverage choices that may, over time, increase risks of obesity, diabetes and other diet-related conditions.

The findings come amid record regional warmth in recent years. The United Kingdom recorded its hottest average summer on record in 2025, and scientists have said that such extremes have been made markedly more likely by anthropogenic climate change. The authors of the new study frame their results as another reason for efforts to slow warming and to design public-health interventions that consider how climate affects behaviour, including choices about hydration and cooling.

The research team calls for policymakers to account for dietary pathways when estimating the health costs of climate change and suggests targeted public-health strategies to promote safer hydration and cooling options, particularly in lower-income communities that may be most affected. The study's authors also emphasize that limiting global warming in line with international goals would reduce the magnitude of the projected dietary shifts.

The study's use of large-scale purchasing data provides a quantitative link between daily temperature and sugar buying, but the authors and independent experts say further work is needed to connect these patterns to clinical outcomes and to test interventions that might mitigate the effect. As the climate continues to warm, the researchers say, attention to indirect, behaviour-mediated health impacts will be important for planning and equity in public health responses.