Coffee drinkers carried less visceral fat at the same BMI

Coffee is one of the most widely consumed sources of bioactive compounds in the world, yet what it does to circulating metabolites, sex hormones and cardiometabolic markers is still incompletely mapped. Most people drink it daily without any clear sense of whether it nudges body composition or hormones at all. Sex hormones are a particularly murky area, because total testosterone, free testosterone and the binding protein SHBG can move in different directions and mean different things. This study set out to characterise those associations in a large general population, with attention to whether men and women differ.

The researchers used data from the Northern Finland Birth Cohort 1966, analysing 2,264 participants, 47% of them men, all assessed at age 46. Coffee intake was compared against body composition, circulating metabolites including branched-chain amino acids, glucose and insulin measures, and a panel of sex hormones covering total testosterone, bioavailable testosterone, free testosterone, SHBG and the free androgen index. Analyses were stratified by sex and used both rank correlations and multivariable linear regression. The regression models were adjusted for BMI, educational attainment, smoking, physical activity and alcohol intake. All measurements came from a single time point, so this is a snapshot rather than a follow-up.

Higher coffee intake groups had lower total and visceral fat and higher skeletal muscle mass, while BMI was comparable across the groups. Coffee intake correlated inversely with circulating branched-chain amino acids in both sexes. In men, higher intake was linked to a more favourable glucose and insulin profile. The hormonal pattern was distinctive: in men, coffee intake was positively associated with total testosterone at about +0.29 nmol/L per cup a day, along with bioavailable testosterone and SHBG, but inversely associated with free testosterone and the free androgen index. In women, the hormonal associations were more limited, restricted to higher SHBG and lower free testosterone and free androgen index.

The finding that body composition differs while BMI does not sits alongside a broader theme in nutrition research: weight alone can hide meaningful differences in fat distribution and muscle. The hormone results complicate any simple story about coffee and testosterone, because total and bioavailable testosterone moved one way while free testosterone and the free androgen index moved the other, with SHBG rising. The authors are explicit that causality is not established and that the specific coffee-derived compounds involved are unidentified. They call for follow-up studies and intervention trials to work out whether coffee drives any of this.

This is a reason to think habitual coffee drinking travels with a leaner body composition and a different hormone profile, not evidence that adding cups will produce either. Because everyone was measured at one moment, people who drink more coffee may differ in other habits that the adjustments could not fully capture. The hormone results are a useful reminder that a single testosterone number can be misleading when the binding protein shifts at the same time. If you already drink coffee, there is nothing here suggesting a change is needed, and nothing here that makes it a body composition tool.