A coffee body composition study from the University of Oulu has found that people who drink more coffee tend to carry less body fat, hold more skeletal muscle, and display distinct hormonal patterns, though the researchers are careful to say the data cannot establish that coffee itself caused any of those differences.
The study, published in the European Journal of Nutrition, drew on data from 2,264 participants in the Northern Finland Birth Cohort 1966 programme. All participants were 46 years old when their health information was collected in 2012, according to FOX 17. Researchers examined how habitual coffee intake related to circulating metabolites, cardiometabolic risk indicators, and sex hormone levels.
What the coffee body composition study actually found
People with higher coffee consumption had lower total body fat and lower visceral fat, alongside greater skeletal muscle mass. Those differences held even though participants who drank more coffee and those who drank less had comparable body mass index scores. The company of researchers also found that higher coffee intake was associated with lower circulating concentrations of branched-chain amino acids, which, when chronically elevated, have previously been linked to insulin resistance and greater type 2 diabetes risk.
One detail worth noting about the sample: only 70 of the 2,264 participants reported drinking no coffee at all, per FOX 17. That lopsided distribution reflects Finland’s status as one of the world’s highest coffee-consuming countries, with average annual consumption of approximately 11.8 kilograms per person. It also means the study had very little data on genuine non-drinkers to use as a comparison point, a constraint the researchers would need to address in any follow-up work.
Hormone patterns differed between men and women
Some of the clearest associations appeared in men. Greater coffee intake was linked to a more favourable glucose-insulin profile, higher levels of total and bioavailable testosterone, and greater concentrations of sex hormone-binding globulin (SHBG). Free testosterone and the free androgen index were, however, modestly lower. The pattern in women was less extensive: higher coffee consumption was mainly associated with increased SHBG and lower measures of free androgens.
Luca Verroest, lead author of the study and Doctoral Researcher at the University of Oulu, described the hormonal signal as the most unexpected element. ‘Coffee is consumed by millions of people every day, yet we still know surprisingly little about how it relates to our metabolism and hormones. What stood out in our findings was a distinct hormonal signature that didn’t disappear even after we took into account BMI and lifestyle factors, with several of these associations differing between men and women,’ Verroest said.
The coffee body composition study raises the possibility that hormonal pathways could help explain some of the previously observed association between coffee consumption and metabolic health. Earlier research has linked coffee drinking with reduced risk of type 2 diabetes and cardiovascular disease, though the biological mechanisms have remained unclear.
Observational design limits what can be claimed
The study’s design is the central caveat. Because the research is observational, it cannot establish that drinking coffee directly produced any of the biological differences identified. People who drink more coffee may differ from lighter drinkers in diet, exercise, sleep or any number of other unmeasured ways, and the study cannot rule those out as explanations.
The researchers acknowledge that further work is needed before these findings can inform dietary guidance. Scientists are currently investigating the relevant questions using animal models, with the longer-term aim of moving toward human intervention studies. Those studies would be better placed to test whether coffee itself is responsible, and, if so, which compounds might be doing the work.
The full citation is: Luca Verroest et al., ‘Associations of habitual coffee intake with testosterone and cardiometabolic markers: the Northern Finland birth cohort 1966 study,’ European Journal of Nutrition, 2026, volume 65, issue 5, DOI: 10.1007/s00394-026-04038-z. The next step the researchers have identified is moving from animal models toward human intervention trials.
