What Will Happen To Your Body If You Don't Drink Coffee For Two Weeks?
- 8.11.2026, 9:57
The scientists' response was surprising.
Giving up coffee for two weeks may seem like a simple change in habits. Fewer espressos in the morning, perhaps a little more sleep in the first few days, and the need to find another way to wake up.
But a new study shows that the changes go much deeper—right into the gut itself, according to El Español.
A study published in 2026 in the journal *Nature Communications* analyzed how regular coffee consumption is linked to the gut microbiome and what happens when daily coffee drinkers stop drinking it for 14 days.
The conclusion is clear: coffee leaves a noticeable “mark” on the gut ecosystem, and part of that mark begins to change when coffee is removed from the diet.
The researchers first compared 31 regular coffee drinkers with 31 people who did not drink coffee. They then asked the first group to completely eliminate coffee for two weeks. After this period, the participants resumed drinking coffee for 21 days—some drank caffeinated coffee, while others drank decaffeinated coffee.
Diet was monitored using food diaries, and, with the exception of minor deviations, it did not change significantly during the experiment. This made it possible to see more clearly what happens when the beverage is eliminated and then reintroduced.
Coffee Leaves a “Signature”
Before giving up coffee, people who drank it exhibited a different gut microbiota profile compared to those who did not consume it.
In particular, they had higher levels of bacteria from the genera Cryptobacterium and Eggerthella. They also had different levels of several fecal metabolites—including indole-3-propionic acid, indole-3-carboxaldehyde, and GABA. This was followed by 14 days without coffee.
During this period, levels of caffeine, theophylline, and 1,7-dimethylxanthine (a caffeine metabolite) in the stool decreased significantly—which was entirely expected. However, the amount of hippuric acid also decreased, while the amount of indole-3-carboxaldehyde—a metabolite associated with the activity of gut microorganisms—increased.
This means that giving up coffee doesn’t just eliminate the substances that come directly from the beverage. It also alters some of the metabolic processes that occur between the components of coffee, our bodies, and gut bacteria. The story became even more interesting when coffee was reintroduced into the diet.
After two weeks of abstinence, the participants drank four servings of instant coffee daily for three weeks—either caffeinated or decaffeinated. The researchers observed rapid changes in the microbiome after coffee consumption resumed, and some of these changes occurred regardless of whether the coffee contained caffeine.
This suggests that it’s not just about the stimulant that helps us stay awake. Coffee contains a complex mixture of polyphenols, phenolic acids, melanoidins, and other compounds that can enter the gut and serve as “food” for certain bacteria.
This link has already been observed in previous studies
A large-scale analysis published in *Nature Microbiology* examined data from tens of thousands of people and found a particularly strong link between coffee consumption and the presence of the bacterium *Lawsonibacter asaccharolyticus*.
The link was so pronounced that, out of more than 150 foods analyzed, coffee stood out as having the strongest association with certain gut microorganisms.
However, detecting changes in the microbiome does not necessarily mean that giving up coffee is automatically better for the gut. This is perhaps the most important caveat.
The 2026 study describes differences and changes, but does not claim that the gut microbiome profile of non-coffee drinkers is healthier than that of coffee drinkers, or that two weeks of abstinence provides any specific clinical benefit. Not all of the observed effects were straightforward.
Regular coffee drinkers initially exhibited greater impulsivity and emotional reactivity, as well as poorer memory, compared to those who did not drink coffee.
During abstinence, some measures of attention and alertness improved, but after resuming consumption—of both caffeinated and decaffeinated coffee—their levels of perceived stress and some self-reported symptoms of depression decreased.
In other words, coffee does not act like a switch with “good” or “bad” settings. Moreover, the experiment was relatively small and involved healthy adults. To understand what these changes mean in the long term, larger-scale studies and long-term follow-ups will be needed.
Regular coffee consumption promotes certain bacterial and metabolic processes. Giving it up for just 14 days already begins to alter this picture, and resuming consumption leads to new changes within a matter of days.
Therefore, giving up coffee for two weeks is not just about skipping a single cup in the morning. It also involves, at least temporarily, a change in the activity of the bacteria living in our gut.