Scientists found that higher caffeine levels in the blood are linked to lower body fat and a reduced risk of type 2 diabetes. This suggests that caffeine, especially from calorie-free drinks, might help manage body fat and diabetes risk. Researchers from the Karolinska Institute, University of Bristol, and Imperial College London analyzed genetic data from nearly 10,000 people to explore how caffeine breakdown in the body affects weight and diabetes. 

They focused on genes that control caffeine metabolism, like CYP1A2 and AHR, which influence how quickly caffeine leaves the bloodstream. People with genetic variations that slow caffeine breakdown tend to keep caffeine in their blood longer but usually consume less caffeine overall. Using a method called Mendelian randomization, the team found that higher genetically predicted caffeine levels were linked to lower body mass index (BMI) and less whole-body fat, which in turn lowered diabetes risk. About half of caffeine’s protective effect against diabetes appeared to be due to its influence on body fat reduction. 

However, no clear connection was found between caffeine levels and heart diseases like stroke or heart failure. Scientists believe caffeine may boost metabolism by increasing heat production and fat burning in the body, but more research is needed to confirm these effects and understand long-term impacts. The study highlights how even small effects of caffeine on metabolism could have important health benefits worldwide.