<p>The environmental changes, such as global warming, are expected to impact people’s health in various ways, including their diet. Quantifying these effects is challenging due to the high cost and limited scalability of traditional survey methods. The rise of the online food delivery (OFD) industry offers an alternative approach, with its rich data providing large-scale insights into dietary health. In this study, we, for the first time, analyze the association between extreme heat and dietary consumption behaviors using real-world OFD data. Our dataset includes 4,285,046 orders across six food categories from a leading Chinese OFD platform. We examined ordering patterns at three levels: overall orders, by food category, and by specific dishes. Using Autoregressive Integrated Moving Average (ARIMA) models, we found that high temperatures were associated with an increase in OFD sales. Notably, the “Drinks" category showed a significant increase in sales. Among the top 10 dishes with the greatest heat-associated demand surge, five were sweetened drinks, particularly milk tea. By mapping these changes with temperature rise in daily scale, we predicted shifts in urban residents’ dietary behaviors in the context of global warming. Our findings underscore the importance of adapting OFD services to protect consumers’ dietary health during heat waves, reducing the potential negative health impacts of extreme heat.</p>