Coffee Drinkers Show Leaner Body Composition And Distinct Hormone Patterns, New Finnish Study Finds

A new study from researchers in Finland has found that adults who drink more coffee tend to have leaner body composition and distinct hormonal profiles compared with lighter coffee drinkers, adding new detail to the long-running scientific effort to understand why coffee consumption has repeatedly been linked to a lower risk of conditions such as type 2 diabetes and cardiovascular disease.

The study, conducted at the University of Oulu, analyzed data from 2,264 participants, all 46 years old, who are part of the Northern Finland Birth Cohort 1966, a long-running population study. Researchers examined how habitual coffee consumption related to circulating metabolites, cardiometabolic risk markers and sex hormones. The findings were published July 16 in the European Journal of Nutrition.

Despite having similar body mass index measurements, participants who consumed more coffee had lower total and visceral fat and greater skeletal muscle mass than those who drank less coffee, according to the study. In both men and women, higher coffee consumption was also associated with lower circulating levels of branched-chain amino acids, biomarkers that previous research has linked to insulin resistance and an increased risk of type 2 diabetes when chronically elevated.

The most pronounced hormonal differences emerged specifically among men. Higher coffee consumption in male participants was linked to a more favorable glucose-insulin profile, along with higher concentrations of total and bioavailable testosterone and increased levels of sex hormone-binding globulin, a protein that regulates how much testosterone circulates freely in the bloodstream. At the same time, free testosterone and the free androgen index, a separate measure of androgen activity, were modestly lower among men who drank more coffee. In women, hormonal associations were more limited, primarily showing up as higher sex hormone-binding globulin levels and lower measures of free androgens.

Luca Verroest, the study's lead author and a doctoral researcher at the University of Oulu, said the findings point to a distinct biological signature tied to coffee consumption that held up even after accounting for other factors. "Coffee is consumed by millions of people every day, yet we still know surprisingly little about how it relates to our metabolism and hormones," Verroest said, adding that the hormonal pattern observed in the study "didn't disappear even after we took into account BMI and lifestyle factors," and that several of the associations differed notably between men and women.

The research team said the results suggest hormonal pathways may play a role in explaining the broader relationship between coffee consumption and metabolic health that has been documented in earlier studies. However, because the study was observational, meaning researchers analyzed existing data rather than conducting a controlled experiment, the findings demonstrate associations rather than establishing a direct cause-and-effect relationship between coffee intake and the metabolic and hormonal differences observed.

The study carries particular relevance in Finland, which ranks among the highest coffee-consuming countries in the world, with annual per-person consumption averaging around 11.8 kilograms, or roughly 26 pounds, of coffee. That high baseline consumption across the study population may have made it easier for researchers to detect meaningful differences between higher- and lower-consuming groups within the cohort.

Looking ahead, the research team said the findings provide a foundation for future studies aimed at determining whether coffee itself directly drives the observed biological changes, and at identifying which specific compounds within coffee might be responsible. According to the University of Oulu, those questions are currently being investigated in animal models, with the longer-term goal of eventually progressing to human intervention studies, in which researchers would directly test coffee's effects under controlled conditions rather than relying solely on observational population data. The researchers cautioned that further research will be needed before the findings could be used to inform formal dietary recommendations.

The new study adds to a broader body of research examining coffee's relationship to human health, an area that has produced a wide range of findings over the years, some more consistent than others. Earlier research has linked moderate coffee consumption to a range of potential benefits, including reduced risk of type 2 diabetes and cardiovascular disease, though the precise biological mechanisms behind those associations have remained an active area of scientific investigation. The Oulu team's focus on sex hormones and detailed metabolic markers offers a more granular look at some of the physiological pathways that might underlie those previously observed associations.

The study was conducted by researchers affiliated with the University of Oulu's Research Unit of Biomedicine and Internal Medicine and its Arctic Biobank infrastructure for population studies, with additional contributions from researchers at Poznan University of Medical Sciences in Poland, Imperial College London and Brunel University London. All participants provided written informed consent, and the study was approved by the Ethical Committee of the Northern Ostrobothnia Hospital District in Oulu, Finland.

With coffee remaining one of the most widely consumed beverages in the world, researchers say understanding its underlying biological effects on metabolism and hormone regulation could eventually help inform more precise, evidence-based guidance around its consumption, though for now, the study's authors are clear that its findings represent an association worth investigating further rather than a basis for new dietary advice.