- A study of 2,264 participants from the Northern Finland Birth Cohort 1966 found that higher coffee intake is associated with lower body fat and higher muscle mass.
- Men who drank more coffee showed higher levels of total and bioavailable testosterone, but lower free testosterone.
- Both men and women who drank more coffee had higher levels of sex hormone-binding globulin (SHBG) and lower levels of branched-chain amino acids (BCAAs), which are linked to insulin resistance.
- Researchers noted the study is cross-sectional, meaning it can show associations but cannot prove that coffee causes these effects.
- The findings suggest a potentially favorable metabolic profile for male coffee drinkers, though causality remains unproven.
For millions of Americans, the morning coffee ritual is less a choice than a necessity—a steaming gateway to productivity and a barrier against the pre-10 a.m. fog. But a new study from Finland suggests that daily brew may be doing more than sharpening focus; it could be reshaping hormonal profiles and body composition in ways that differ significantly between men and women. Researchers from the Northern Finland Birth Cohort 1966 presented their findings on the association between habitual coffee intake and key metabolic markers at the age of 46, offering a compelling glimpse into the complex relationship between diet and endocrine health. The study, which analyzed data from 2,264 adults, found that men who consumed more coffee exhibited higher total and bioavailable testosterone, while both sexes showed lower levels of branched-chain amino acids and a leaner body composition. The research was published in the journal Scientific Reports.
The Finnish advantage: Why this cohort matters
Finland is an ideal location for this research, holding the distinction of the world’s highest per-capita coffee consumption. This high baseline allowed researchers to analyze a wide spectrum of drinking habits, from abstainers to heavy consumers. All participants were part of the Northern Finland Birth Cohort 1966, a longitudinal study that has tracked the same individuals since their birth. At age 46, participants reported their daily coffee intake and underwent fasting blood tests and body measurements. The researchers controlled for a range of potential confounding factors—including body mass index (BMI), education, smoking, physical activity and alcohol use—to isolate the specific associations with coffee.
Hormonal divergence: Men’s testosterone and SHBG
The most distinctive finding was a clear sex-specific pattern in hormone levels. In men, each additional cup of coffee per day was associated with a measurable increase in total testosterone and bioavailable testosterone—the portion available for tissues to use. However, this was coupled with a concurrent rise in sex hormone-binding globulin (SHBG), a protein that binds to sex hormones and regulates their availability. Because of the SHBG increase, free testosterone—the unbound, immediately usable form—was actually lower. Researchers described this pattern as potentially "hormonally favorable" for men, given its links to improved insulin sensitivity and lower visceral fat. Women also showed higher SHBG and lower free testosterone with higher coffee intake, but their total and bioavailable testosterone did not change.
Body composition and metabolic markers
Beyond hormones, the study revealed an inverse relationship between coffee intake and markers of metabolic risk. Both men and women who drank more coffee exhibited lower levels of branched-chain amino acids (BCAAs), which are often elevated when insulin resistance is developing. Heavy coffee drinkers also tended to have less total and visceral fat—the dangerous fat stored around internal organs—and more skeletal muscle, even when their overall BMI was similar to lighter drinkers or non-drinkers. In men, these differences were accompanied by lower fasting insulin and better insulin sensitivity.
A note of caution: Correlation versus causation
While the associations are notable, the study is observational and cross-sectional, meaning it captures a single point in time and cannot establish cause and effect. Researchers emphasize that they did not assign participants to specific coffee regimens, so it remains possible that men with naturally higher testosterone simply prefer coffee. The study cannot determine whether coffee itself produces these changes, whether the effects would vary by preparation method, or whether the results would hold in a different population. The findings are population-level patterns, not measurable shifts an individual would notice in their daily life.
A promising brew, a measured pour
The picture emerging from Finland is not an endorsement to dramatically increase consumption, nor a call to abandon the habit. For the average 46-year-old, coffee appears to travel with a leaner physique and, in men, a particular hormonal profile that may support metabolic health. But these are associations, not guarantees. The next step requires longitudinal and intervention studies to determine whether coffee’s bioactive compounds hold the credit, and whether the benefits extend to other ages and demographics. Until then, the study offers a fascinating rationale for why your morning cup might be doing more than just waking you up!
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