A new Finnish study suggests that habitual coffee consumption may be linked to changes in sex hormones, body fat, muscle mass and glucose metabolism, particularly in men.
For millions of people, coffee is an essential part of the morning routine. But beyond helping people feel more alert, new research suggests that regular coffee consumption may also be associated with subtle changes in the body’s hormones and metabolism.
Researchers from the University of Oulu in Finland analysed health data from 2,264 middle-aged adults and examined their coffee consumption alongside sex hormones, body composition, blood metabolites and cardiometabolic markers.
The findings, published in the European Journal of Nutrition, revealed several interesting associations. People who consumed more coffee tended to have less total and visceral fat and greater skeletal muscle mass, despite having broadly similar body mass indexes.
The researchers also found a particularly interesting relationship between coffee consumption and testosterone in men.
However, experts caution that the research was observational. That means the findings show an association between coffee drinking and hormone levels, but they do not prove that coffee itself causes hormonal changes.
Key Findings From the Coffee and Hormone Study
The Finnish research uncovered several notable patterns among people who regularly drank coffee.
The main findings included:
- Higher coffee intake was associated with lower total body fat.
- Coffee drinkers also tended to have less visceral fat, the type of fat stored around internal organs.
- Higher coffee consumption was associated with greater skeletal muscle mass.
- Men who drank more coffee showed a more favourable glucose-insulin profile.
- In men, greater coffee intake was associated with higher total testosterone and bioavailable testosterone.
- Coffee consumption was also associated with higher levels of sex hormone-binding globulin (SHBG).
- At the same time, men showed slightly lower free testosterone and free androgen index levels.
- In women, the hormonal associations were more modest, with higher SHBG and lower free testosterone and free androgen index.
- Coffee consumption was associated with lower circulating levels of several branched-chain amino acids (BCAAs) in both sexes.
The study therefore points towards a potentially complex relationship between coffee, metabolism and sex hormones rather than a simple “coffee raises testosterone” effect.
Researchers Studied More Than 2,200 Middle-Aged Adults
The study was based on participants from the Northern Finland Birth Cohort 1966, a long-running population study.
Researchers analysed data from 2,264 participants, of whom approximately 47% were men. The participants were around 46 years old when the relevant data were collected.
Among the participants:
- 2,194 were coffee consumers
- 70 reported consuming neither coffee nor tea
- 296 participants consumed around 1–2 cups per day
- 822 consumed around 3–4 cups per day
- 1,076 consumed five or more cups per day
The researchers assessed coffee consumption through questionnaires and compared it with measurements of body composition, blood metabolites, glucose-insulin markers and hormones.
Their statistical models also accounted for several factors that could influence the results, including BMI, education, smoking, physical activity and alcohol consumption.
More Coffee Was Linked to Less Body Fat
One of the most interesting findings concerned body composition.
People in the higher coffee-consumption groups generally had:
- Lower body-fat percentage
- Lower total body-fat mass
- Lower visceral fat area
- Higher skeletal muscle mass
Importantly, their overall BMI was similar across the coffee-consumption groups.
This matters because BMI does not distinguish between fat and muscle or show where fat is stored. Visceral fat, in particular, is metabolically active and has been associated with an increased risk of conditions such as insulin resistance and type 2 diabetes.
The researchers suggest that caffeine could potentially contribute to some of these differences because caffeine can stimulate the sympathetic nervous system, which may increase resting energy expenditure and thermogenesis.
Thermogenesis refers to the production of heat by the body. Caffeine may also promote lipolysis, the process through which stored fat is broken down.
However, these biological mechanisms remain a possible explanation rather than proof that coffee caused the differences in body composition.
Coffee and Testosterone: What Happened in Men?
The strongest hormone-related findings appeared in men.
Men who consumed more coffee showed higher concentrations of total testosterone. After adjusting for important lifestyle and health factors, the researchers found that each additional cup of coffee per day was associated with an increase of approximately 0.29 nmol/L in total testosterone.
Higher coffee intake was also associated with:
- Higher bioavailable testosterone
- Higher SHBG
- Lower free testosterone
- Lower free androgen index
At first glance, those results may appear contradictory.
How can total testosterone be higher while free testosterone is lower?
The answer involves how testosterone travels through the bloodstream.
What Is Bioavailable Testosterone?
Not all testosterone circulating in the blood is equally available for the body’s tissues to use.
Some testosterone circulates freely, while another portion is attached to proteins.
Bioavailable testosterone generally refers to testosterone that is free or loosely bound to albumin and therefore more readily available to tissues.
The study found that greater coffee consumption in men was associated with higher total and bioavailable testosterone, but also with higher SHBG and lower free testosterone.
This means the relationship between coffee and testosterone is considerably more complicated than the popular claim that “coffee boosts testosterone”.
What Is SHBG?
Sex hormone-binding globulin, or SHBG, is a protein produced mainly by the liver.
It binds to sex hormones, including testosterone and oestrogen, and helps regulate how much of those hormones remains available to tissues.
The Finnish researchers found a positive association between coffee consumption and SHBG in both men and women.
In men, each additional daily cup of coffee was associated with an increase of approximately 0.57 nmol/L in SHBG in the fully adjusted model.
In women, the association was approximately 1.27 nmol/L per additional cup per day.
Why Free Testosterone Can Be Lower Even When Total Testosterone Is Higher
This is one of the most important details in understanding the study.
When SHBG increases, more testosterone can become bound to SHBG.
Consequently, someone can have:
Higher total testosterone + higher SHBG + lower free testosterone
at the same time.
Therefore, it would be misleading to report this research simply by saying that “coffee increases testosterone”.
The actual findings show a more complicated hormonal profile, especially among men.
The researchers themselves describe the pattern as sex-specific, with higher coffee consumption associated with total and bioavailable testosterone and SHBG but lower free testosterone and free androgen index in men.
What Did the Study Find in Women?
The hormonal associations were less pronounced in women.
Among women, higher coffee intake was associated with:
- Higher SHBG
- Lower free testosterone
- Lower free androgen index
However, researchers did not find significant associations between coffee consumption and total testosterone or bioavailable testosterone.
The female analysis was also restricted to women who had available information about polycystic ovary syndrome and who did not report having PCOS.
This difference between men and women highlights the importance of studying hormonal responses separately rather than assuming coffee affects everyone in the same way.
Coffee Was Also Linked to Glucose and Insulin Metabolism
The study was not only about sex hormones.
Researchers also investigated markers associated with glucose and insulin metabolism.
Among men, higher coffee consumption was associated with:
- Lower fasting insulin
- Lower insulin responses during glucose testing
- Lower measures of insulin resistance
- Greater insulin sensitivity
Men who drank more coffee therefore showed a more favourable glucose-insulin profile.
This finding is particularly interesting because previous research has linked coffee consumption with a lower risk of type 2 diabetes.
The new study suggests that hormonal and metabolic pathways may be connected, although the researchers emphasise that their findings cannot establish a cause-and-effect relationship.
Could Coffee’s Hormonal Effects Help Explain Diabetes Risk?
The researchers suggest that sex hormones and SHBG could potentially be part of the biological pathway connecting coffee consumption with metabolic health.
SHBG is particularly interesting because lower SHBG concentrations have previously been associated with an increased risk of type 2 diabetes in both men and women.
The Finnish findings showed higher SHBG among people consuming more coffee.
This does not mean coffee should be considered a treatment or prevention strategy for diabetes. Instead, the results provide another possible piece of the puzzle explaining why coffee consumption has been associated with certain favourable metabolic outcomes in previous research.
More research is needed to determine whether these hormonal changes actually contribute to improved long-term health.
Coffee Consumption Was Also Associated With Metabolites
The researchers used advanced blood metabolomics to examine hundreds of metabolic measurements.
One notable finding was an inverse association between coffee intake and several branched-chain amino acids, or BCAAs.
These include:
- Leucine
- Isoleucine
- Valine
The association was observed in both men and women.
BCAAs are essential amino acids that play important roles in muscle metabolism and other biological processes. Changes in circulating BCAA levels have also been investigated in relation to insulin resistance and metabolic health.
However, the researchers noted that most of the observed correlations were relatively small, meaning these findings should be interpreted cautiously.
Does This Mean Drinking More Coffee Is Better?
Not necessarily.
This is one of the most important conclusions readers should take from the research.
The study found associations between habitual coffee consumption and several favourable body-composition and metabolic measures, but it does not prove that increasing coffee intake will produce those benefits.
There are several reasons for caution.
The study was cross-sectional, meaning researchers examined participants’ data at a particular point in time. They could identify relationships between coffee consumption and hormone levels, but they could not determine which factor came first.
For example, it is possible that people with particular lifestyles or metabolic characteristics were more likely to drink coffee.
The researchers adjusted their analyses for several potential confounding factors, but statistical adjustment cannot eliminate every possible source of bias.
The Study Has Important Limitations
As with any observational nutrition study, the results need to be interpreted in context.
Important limitations include:
- The research was observational and cross-sectional.
- Coffee consumption was self-reported.
- The questionnaire did not specify a standard cup volume.
- Coffee type and brewing methods can vary considerably.
- Lifestyle differences existed between coffee-consumption groups.
- Higher coffee consumers were more likely to smoke.
- The research cannot prove that coffee directly changed hormone levels.
- The study involved middle-aged Finnish adults, so the findings may not apply equally to every population.
- Long-term intervention studies are needed to establish causality.
The researchers specifically call for longitudinal and intervention studies to determine whether coffee-derived compounds directly influence hormones and metabolism.
So, Should You Keep Drinking Your Morning Coffee?
For people who already enjoy coffee, these findings provide another interesting reason to study what happens inside the body after regular coffee consumption.
But the research should not be interpreted as a recommendation to dramatically increase caffeine intake.
Coffee affects people differently, and factors such as caffeine sensitivity, sleep, anxiety, blood pressure, medications and the amount of sugar or high-calorie additions in a drink can all matter.
A plain cup of coffee is also very different nutritionally from a large coffee beverage loaded with added sugar, syrups and cream.
The broader message is that coffee is biologically active and its effects may extend beyond temporary alertness.
What This New Research Really Tells Us
The Finnish study adds an intriguing new dimension to the growing body of research on coffee and health.
Rather than showing a simple relationship between caffeine and testosterone, it suggests that habitual coffee consumption may be associated with a complex hormonal and metabolic profile.
In men, higher coffee consumption was associated with:
- Higher total testosterone
- Higher bioavailable testosterone
- Higher SHBG
- Lower free testosterone
- Lower free androgen index
- More favourable glucose-insulin markers
- Lower body fat
- Lower visceral fat
- Greater skeletal muscle mass
In women, researchers observed:
- Higher SHBG
- Lower free testosterone
- Lower free androgen index
- Less pronounced hormonal associations overall
These findings demonstrate why looking at a single hormone measurement can sometimes give an incomplete picture of how diet and lifestyle interact with the endocrine system.
The Bottom Line
Coffee is much more than a morning pick-me-up.
New research from Finland suggests that habitual coffee consumption is associated with differences in body composition, glucose metabolism and sex hormone levels, with the strongest hormonal associations appearing in men.
The study found that heavier coffee consumption was linked to lower total and visceral fat and greater skeletal muscle mass. In men, it was also associated with higher total and bioavailable testosterone and SHBG, while free testosterone and free androgen index were lower.
Women showed a more modest hormonal pattern, mainly involving SHBG and free testosterone.
But there is an important caveat: association does not equal causation. The research does not prove that coffee directly changes testosterone or protects against diabetes.
For now, the findings offer another fascinating insight into how a familiar daily drink may interact with the body’s metabolism and hormones. And for regular coffee drinkers, there is certainly no need to panic about that morning cup.
In short: coffee may be influencing more of your biology than you realise, but scientists still need more evidence to understand exactly how and why.
Sources and References
- Verroest L, Jokelainen J, Choudhary S, et al. Associations of habitual coffee intake with testosterone and cardiometabolic markers: the Northern Finland birth cohort 1966 study. European Journal of Nutrition, 2026. Published 16 July 2026.
- PubMed record for the study, including authors, DOI, study design and key findings.
- Full-text study available through PubMed Central.
   For Health & Fitness Products, Click => http://tinyurl.com/5n872ptd
Â