We’ve all experienced how a well-timed matcha can make us feel a little sharper in morning meetings or how a too-late latte can mess with our sleep, but caffeine does more to our bodies and hormones than just keep us feeling perky and alert. Caffeine can raise cortisol levels, spike blood sugar (even black coffee), and even affect estrogen and other sex hormones.
Thankfully, there is no need to totally ditch your daily wake-up ritual but understanding the link between caffeine and your hormones can help you decide the type of caffeine you want to consume, how much, and at what times of day.
Cortisol sometimes gets a bad rap as the stress hormone, but a healthy amount is necessary to help us feel alert and awake and to maintain things like skin health, blood pressure, heart rate, digestion, and our reproductive systems.
Natural levels of cortisol usually peak sometime around 8:30 or 9 a.m., typically when a lot of people are enjoying their first (or second, no judgment) coffee of the day. The potential issue here is that drinking coffee at this time may interfere with the body’s natural cortisol production— the body is getting that cortisol burst from the caffeine, so why make its own? This can cause a whole host of symptoms, including fatigue, mood changes, and skin coloration changes to name a few.
Time of Day Tip for Cortisol & Caffeine: If you can stand to wait it out, mid-to-late morning is the best time to drink coffee to get the full benefit without disrupting your natural cortisol production or risking a sleepless night.
There is a link between caffeine and estrogen, but strangely whether caffeine increases or decreases estrogen seems to depend on your race. One study from the National Institutes of Health (NIH) found that Asian women who consumed 200 milligrams of coffee per day (about two cups of drip or one 16-ounce cold brew) showed elevated estrogen levels. However white women who consumed the same amount had slightly lower estrogen levels compared to women of the same race who had less caffeine. Black women who drank 200 milligrams showed a very slight increase in estrogen levels which was deemed statistically insignificant.
For estrogen balance, the type of caffeine may matter: The study found that for all groups, consuming more than one cup each day of caffeinated soda or green tea was associated with higher estrogen levels. So, if you’re dealing with low estrogen due to an imbalance or menopause, you may want to reach for a green tea or matcha instead of that cup of joe.
Estrogen in Fertility
While the NIH study showed changes in estrogen levels depending on race and the type of caffeine consumed, caffeine consumption did not appear to affect ovulation in any group as long as it was limited to 200 mg or less per day. (That’s two 8-ounce cups of coffee.)
But this doesn’t just apply to women. The NIH also recommends that men stick to this limit while you’re trying to conceive, and not just as a show of moral support.
The nice thing is, once you get used to limiting yourself to two cups a day, the guideline stays the same once you are pregnant. This infamous limit (who hasn’t sympathized with a pregnant woman groaning about sacrificing caffeine) exists because of the potential link between miscarriage and higher levels of caffeine, though the reasons for this are not yet totally understood.
What is known is that caffeine and estrogen are processed by the same system in the body, so the more caffeine in your body, the longer it takes you to process estrogen. You can picture this like being in a line for self-checkout that gets longer as caffeine cuts in.
While these rules are generally applied to women interesting in becoming pregnant, they also can apply to women who have particularly rough periods, including heavy or painful periods and intense symptoms of PCOS. An older study found that women in their early follicular phase (first day of period through ovulation) who drank 500 mg of coffee or more per day (so somewhere between three and five cups, depending on the strength) had as much as 70% more estrogen in their bodies.
The golden caffeine and fertility rule: Don’t stress about having a bit of coffee each day but limiting yourself to two cups is the sweet spot when it comes to keeping your estrogen levels in balance during conception, pregnancy, or if you experience more severe periods.
For most people, caffeine does not negatively affect insulin resistance or sensitivity. But if high blood sugar is a problem for you, you may want to consider looking into whether or not you are one of the people that, according to the Centers for Disease Control, is extra-sensitive to caffeine. For those who have this increased sensitivity, even black coffee can influence blood sugar levels.
The insulin-caffeine connection is personal: Most people don’t need to worry about a cup of black coffee spiking their insulin. But for those whose bodies have trouble maintaining balanced insulin, consider whether your daily cup (or more) of joe may be having an adverse effect.
The bottom line is there’s no need to go cold turkey on the caffeine (thank God). A little bit of it even has some good health benefits. But whether you like an occasional iced matcha or drink a few cups of coffee a day, it’s a good idea to periodically look at how much caffeine you’re consuming and when you’re drinking it to make sure that it’s working with your natural hormone balance and not against it.