Coffee drinkers who reach for another cup tend to carry less body fat and more muscle at midlife than lighter drinkers, a Finnish study reports, even when their body mass index looks the same. The findings come from an observational analysis of the Northern Finland Birth Cohort 1966, published in the European Journal of Nutrition on July 16, 2026.
Researchers at the University of Oulu drew on data from 2,264 adults, all age 46. They tracked how habitual coffee intake lined up with metabolites, cardiometabolic risk markers and sex hormones, adjusting for BMI, education, smoking, physical activity and alcohol.
The body-composition contrast is what stood out. Two people can share a BMI while carrying very different amounts of fat and muscle, and the heavier coffee drinkers landed on the leaner side.
Sex-specific hormone patterns
In both sexes, higher coffee intake tracked with lower circulating levels of branched-chain amino acids, molecules that have been linked to insulin resistance and greater risk of type 2 diabetes when chronically elevated.
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Men showed the strongest signals. Higher coffee intake was tied to a more favorable glucose-insulin profile and to higher total and bioavailable testosterone.
Sex hormone-binding globulin (SHBG), a carrier protein that lowers the share of testosterone freely available to tissues, was also higher in heavier coffee drinkers. Free testosterone and the free androgen index came out modestly lower.
In women, the hormonal picture was thinner. The main signals were higher SHBG and lower free androgens.
"Coffee is consumed by millions of people every day, yet we still know surprisingly little about how it relates to our metabolism and hormones," said Luca Verroest, a doctoral researcher at the University of Oulu who led the study.
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What the study can and cannot say
The design is cross-sectional and observational, so it captures associations rather than cause and effect. People who choose to drink more coffee may also differ in ways the researchers could not fully account for, and the participants were all Finnish adults at a single age.
Even so, the findings sit on top of a large body of earlier evidence linking moderate coffee intake to lower risk of cardiovascular disease and type 2 diabetes. The American Heart Association considers up to five cups of caffeinated coffee a day safe for most adults.
Harvard's Nutrition Source notes that a habit of three to five cups has been linked to about 15 percent lower cardiovascular disease risk. Earlier randomized work has also pushed back on the once-standard advice for heart patients to avoid coffee.
None of that turns coffee into a weight-loss tool. Loading a cup with sugar and cream can dilute any benefit, and anyone with heart, sleep or anxiety issues should talk with their doctor about caffeine. The Oulu team says more research is needed before the results can shape any dietary recommendations.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.