Finnish study: coffee drinkers show less fat, more muscle and distinct hormone patterns
Researchers at the University of Oulu found that habitual coffee consumption is linked to healthier body composition and differing sex hormone patterns in men and women. Because the study is observational, it cannot prove coffee directly causes these effects.
Scientists at the University of Oulu in Finland examined how regular coffee intake relates to metabolic markers and sex hormone levels, analyzing data from 2,264 people aged 46 who are part of the long-running Northern Finland Birth Cohort 1966 study.
Less fat, more muscle
People who drank more coffee generally had lower total and visceral fat, along with greater skeletal muscle mass, even though body mass index (BMI) was similar regardless of coffee intake. Higher coffee consumption was also linked to lower blood levels of branched-chain amino acids in both sexes — compounds previously associated, when chronically elevated, with insulin resistance and greater risk of type 2 diabetes.
Different hormone patterns by sex
The clearest differences appeared in men, where higher coffee intake was associated with a more favorable glucose-insulin profile, higher total and bioavailable testosterone, and greater sex hormone-binding globulin (SHBG), though free testosterone and the free androgen index were modestly lower. In women, hormonal associations were less extensive, mainly showing higher SHBG and lower free androgen measures.
Lead author Luca Verroest, a doctoral researcher at the University of Oulu, said the hormonal pattern persisted even after accounting for BMI and lifestyle factors, with several associations differing between men and women.
Observation, not proven cause
Because the research is observational, it cannot establish that coffee directly causes the biological differences found. Finland is among the world's top coffee-consuming countries, with average annual consumption of about 11.8 kilograms per person. Researchers are now studying the questions using animal models, aiming eventually to move toward human intervention studies to determine whether coffee itself drives these changes and which compounds might be responsible. Further research is needed before the findings could inform dietary recommendations.
