From the Research
Consuming caffeine on an empty stomach can significantly increase cortisol levels, and to minimize this impact, it's best to eat something before having caffeine or delay the first caffeine intake until mid-morning. Cortisol, your body's primary stress hormone, naturally peaks in the morning upon waking. When you drink coffee or other caffeinated beverages without food, the caffeine stimulates additional cortisol production, potentially amplifying your body's stress response. This effect is most pronounced when caffeine is consumed in the morning between 8-9 AM when cortisol levels are already naturally elevated. The most recent and highest quality study, 1, found that habitual caffeine use is associated with heightened cortisol reactivity to lab-based stress, which supports the idea that caffeine can increase cortisol levels. Some key points to consider:
- Eating a small snack containing protein and complex carbohydrates before having caffeine can help buffer the cortisol response.
- Delaying the first caffeine intake until mid-morning (around 9:30-11:30 AM) when natural cortisol levels have begun to decline can also minimize the impact.
- The typical dose that triggers this response is around 200mg of caffeine (equivalent to a standard 8oz cup of coffee).
- People with anxiety disorders, adrenal issues, or those who are particularly sensitive to stress may want to be especially mindful of this effect, as chronically elevated cortisol can contribute to anxiety, sleep disturbances, and other health issues over time, as noted in 2 and 3. It's also worth noting that while some studies, such as 4 and 5, have explored the effects of caffeine on cortisol levels, the most recent study 1 provides the strongest evidence for the impact of habitual caffeine use on cortisol reactivity.