People who drink coffee regularly tend to have less body fat and more skeletal muscle than those who do not, according to a study drawing attention. Sex hormone markers also moved in different directions for men and women depending on how much coffee they consumed.
Coffee consumption was linked to body composition as well as some metabolic markers and sex hormone levels, according to research by a team at the University of Oulu in Finland published in the European Journal of Nutrition on the 1st.
The researchers used data from 2,264 men and women aged 46, comparing habitual coffee intake with metabolites in the body, markers related to blood sugar and cardiovascular health, and sex hormone levels including testosterone.
The study was an observational one that compared coffee-drinking habits and health status at a single point in time, rather than tracking participants over an extended period.
The analysis found that people who drank more coffee tended to have less accumulated body fat and more skeletal muscle. Body mass index, calculated from weight and height, showed no clear differences by coffee intake.
In other words, even among people with similar BMI figures, differences were observed in body composition, including fat and muscle, depending on how much coffee they drank.
Differences by sex stood out in the link with sex hormones. Among men, higher coffee intake was associated with relatively favorable blood sugar and insulin markers, along with a tendency toward higher concentrations of both total testosterone and the form of testosterone the body can actually use. Sex hormone-binding globulin (SHBG), which carries sex hormones in the blood, was also higher.
Among women, the same associations did not appear clearly. Women who drank more coffee tended to have higher SHBG levels but lower levels of the freely available form of androgens, including testosterone.
Luka Verrust, a nutrition researcher at the University of Oulu who led the study, said millions of people drink coffee every day but less is known than expected about how it relates to metabolism and hormones. Distinct hormonal characteristics remained even after accounting for BMI and lifestyle factors, and some associations differed between men and women, the researcher said.
The study also examined the relationship between coffee and branched-chain amino acids (BCAAs) in the blood. Among both men and women, higher coffee consumption was associated with lower blood BCAA concentrations.
BCAAs are essential amino acids that make up proteins and are needed for muscle synthesis, but earlier studies have found that persistently elevated blood concentrations can be linked to insulin resistance and the risk of metabolic disorders including type 2 diabetes, cardiovascular disease, fatty liver and hypertension.
The research team said the inverse relationship between coffee intake and blood BCAA concentrations in both men and women was particularly noteworthy.
The findings should not be read as evidence that drinking large amounts of coffee reduces body fat or increases muscle mass and testosterone.
A range of factors can affect the results, including the type of coffee, roasting and brewing methods, daily intake, smoking status, lifestyle and individual genetic differences.
The study compared coffee intake and health markers at a single point in time and did not establish a direct causal relationship between the two.
The research team said long-term follow-up studies and intervention studies are needed to determine causality and to identify which bioactive compounds derived from coffee are responsible.
