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How does caffeine affect your adrenal health?

By Dr. Sharon Stills, NMD

“I’m useless ‘til I’ve had my morning coffee.” How often have you heard this statement from a coworker, a friend or even yourself? It’s almost a cliché in our culture that to get ourselves going in the morning, we need a caffeine jolt first thing — so many of us reach for coffee, tea or cola before we’ve even gotten dressed or had breakfast.

woman yawning

And you know, there’s nothing wrong with that — in moderation. But for many women, caffeine masks an adrenal imbalance that may be preventing them from restful sleep. If a woman says she simply can’t function in the morning without caffeine — or that she needs “booster cups” later in the day — there could be an issue with her adrenals.

Table of contents

  1. Does caffeine cause adrenal fatigue?
  2. Is tea better than coffee for adrenal fatigue?

Does caffeine cause adrenal fatigue?

Caffeine itself doesn’t necessarily cause adrenal fatigue, but many of the changes our bodies undergo when we use a lot of caffeine can put a strain on our adrenals. If we substitute a cup of coffee for sleep or for a nutritious meal, it can undermine our adrenal health. So let’s take a closer look at how caffeine affects our bodies — and why it’s best to exclude it from an adrenal fatigue diet.

Does coffee increase cortisol?

Caffeine isn’t likely to do most women much harm if it’s just a cup or two a day. Of course, some women are highly sensitive to caffeine, but that’s rare. For many more women, caffeine becomes a problem when it’s used too often or at the wrong time of day (in the evening, for instance). That’s because caffeine disrupts the regular rhythm of cortisol. In effect, it distances you from your natural energy cycles, tricking your body into a state of emergency or high cortisol — which ultimately makes you feel more tired. If you use caffeine to offset fatigue, your solution may actually be part of the problem — especially if you become too wired to rest when the time comes and start reaching for more caffeine.

Balanced levels of hormones

But the adrenal glands don’t just produce stress hormones — they also help to maintain levels of sex hormones as a woman transitions into menopause and her ovarian function tapers off. They just can’t do that when they’re constantly under siege — whether from real stress in your daily life, or from a turbo-charged caffeine hit every few hours, day after day. So indirectly, caffeine may be affecting your hormonal balance.

Another piece of the puzzle is insulin resistance.

Normally when you’re under stress, an increase in cortisol levels will prompt more glucose to be released into your bloodstream. Then your pancreas increases its insulin output, to usher all that extra glucose into your cells, where they can fuel your “superhuman” response to the “threat.”

But in women whose cells are already insulin resistant, studies show that caffeine exaggerates their glucose and insulin responses. That’s one reason why you may experience sudden energy dips in mid afternoon if you’re caffeine-dependent in the morning — not only has the caffeine jolt worn off, but it has affected your insulin activity so much that your blood sugar may drop in the mid afternoon, making you feel fuzzy-headed and fatigued.

So you reach for more caffeine to clear your head, and sometimes more carbs as well, which just makes the cycle repeat all over again — and simultaneously worsens the insulin resistance (particularly if your caffeine is paired with sugar).

Insulin Sensitivity

A lot of factors determine caffeine’s effect on insulin sensitivity. For example, it varies significantly between men and women, what condition the body’s in, whether caffeine is taken when fasting or with meals, and whether it’s paired with carbohydrates — particularly when taken with sugar. But even though we’re still connecting the dots on all this, the data clearly cast caffeine as a highly active metabolic agent that impacts both insulin resistance and adrenal stress imbalance. The two issues compound one another, and it’s very common for women to have both. Which comes first is like the chicken-or-egg question, so for optimal healing, you should address them both at the same time.

Is tea better than coffee for adrenal fatigue — or should you just go cold turkey?

Tea does not appear to have the same insulin-deregulating effects as coffee. In fact, research suggests that tea actually helps reduce blood glucose because of its polyphenol. So if you worry about insulin resistance, tea might be a better option for you. For a committed coffee drinker, of course, that might not work quite as well.

But before you decide swearing off both is the answer, keep something else in mind: Caffeine is not an easy drug to quit for some women. Caffeine is an addictive substance, both physiologically and psychologically, so stopping “cold turkey” may cause you so much stress and discomfort that its absence does you more harm than good. (After all, when healing the adrenals, the goal is to minimize stressors!) So when you’re ready for a caffeine detox, remember that it’s not something that needs to happen all at once. If it takes you a while to cut back, that’s okay. Adrenal healing doesn’t happen overnight, and we wouldn’t want you to expect it to!

The message here is not that you must live the rest of your life without caffeine — rather, you may want to consider a caffeine holiday to help your adrenals heal. But you’ll need to look at your eating habits and stress patterns, too — which will actually be easier if you eliminate the “noise” that caffeine creates between you and your body’s natural rhythms. There are great herbs for energy that can help boost your adrenals too. Once the adrenals recover, you’ll be in a much better place to create a healthier relationship with caffeine.


1 Brain, M., & Bryant, C. 2000. How caffeine works. URL: https://health.howstuffworks.com/caffeine.htm (accessed 08.07.2009).

2 Robinson, L., et al. 2009. Acute caffeine ingestion and glucose tolerance in women with or without gestational diabetes mellitus. J. Obstet. Gynaecol. Can., 31 (4), 304-12. URL: https://www.ncbi.nlm.nih.gov/pubmed/19497149 (accessed 08.07.2009).

  Lane, J., et al. 2008. Caffeine increases ambulatory glucose and postprandial responses in coffee drinkers with type 2 diabetes. Diabet. Care, 31 (2), 221–222.URL: https://care.diabetesjournals.org/content/31/2/221.full (accessed 08.07.2009).

  Lane, J., et al. 2007. Caffeine in coffee exaggerates postprandial hyperglycemia in type 2 diabetes. Endocr. Pract., 13, 239–243. URL (abstract): https://www.ncbi.nlm.nih.gov/pubmed/17599854 (accessed 08.07.2009).

  Graham, T., et al. 2001. Caffeine ingestion elevates plasma insulin response in humans during an oral glucose tolerance test. Can. J. Physiol. Pharmacol., 79 (7), 559–565. www.ncbi.nlm.nih.gov/pubmed/11478588 (accessed 08.07.2009).

3 Lane, J., et al. 2008.

4 Brain, M., & Bryant, C. 2000.

5 Thong, F., & Graham, T. 2002. Caffeine–induced impairment of glucose tolerance is abolished by beta-adrenergic receptor blockade in humans. J. Appl. Physiol., 92 (6), 2347–2352. URL: https://jap.physiology.org/cgi/content/full/92/6/2347 (accessed 08.07.2009).

6 Louie, JCU., et al. 2008. Delayed effects of coffee, tea, and sucrose on postprandial glycemia in lean, young, healthy adults. Asia Pac. J. Clin. Nutr., 17 (4), 657–662. URL: https://www.ncbi.nlm.nih.gov/pubmed/19114405 (accessed 03.10.2011).

7 Stote, K., & Baer, D. 2008. Tea consumption may improve biomarkers of insulin sensitivity and risk factors for diabetes. J. Nutr., 138 (Suppl.), 1584S-1588S.

Last Updated: December 15, 2023
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