For many people, the first morning cup of coffee matters more for waking up and increasing focus than for its health effects. But the results of a study in Finland suggest that higher coffee consumption may be associated with differences in body fat, muscle mass, metabolism, and levels of some hormones; an association that was particularly more notable in men.
Coffee, beyond caffeine
Coffee contains more than a thousand bioactive compounds, including chlorogenic acids with antioxidant properties, and its regular consumption has previously been linked to a reduced risk of type 2 diabetes and heart disease. But its relationship with hormones was not very clear; therefore, according to MindBodyGreen, the researchers this time also examined levels of testosterone and its binding protein, SHBG-two factors that affect body fat and insulin sensitivity.
Study methods
This analysis was conducted on data from 2,264 46-year-old adults from the "Northern Finland Birth Cohort 1966"; a country with the highest per capita coffee consumption in the world. Almost all participants (except 70 people) drank coffee. Their coffee consumption habits were compared with body composition, blood glucose, and hormone levels, and factors such as body mass index, education, smoking, physical activity, and alcohol consumption were also accounted for in the analysis. Because the data were collected at one point in time, the study can only show statistical associations, not causal relationships.
Less fat, more muscle
Those who drank more coffee generally had lower total body fat and visceral fat and higher muscle mass, although their body mass index did not differ much. An important point is that the researchers did not stratify these findings by sex, while men were more represented in the higher-consumption group; therefore this difference cannot be entirely attributed to coffee.
Different hormonal pattern in women and men
In men, higher coffee consumption was associated with increased total testosterone and bioavailable testosterone, but SHBG levels also rose, resulting in reduced free testosterone. In women, increased SHBG and decreased free testosterone were also seen, but unlike men, their total and bioavailable testosterone did not change.
Additionally, in men higher coffee consumption was associated with lower fasting insulin and improved insulin sensitivity. In both sexes, higher coffee intake was associated with lower branched-chain amino acids-which when elevated are typically a sign of insulin resistance.
The researchers emphasize that these findings do not mean that drinking coffee necessarily causes reduced fat, increased muscle, higher testosterone, or improved insulin sensitivity. This is an observational study and merely shows a statistical association in the population studied, not that every individual will experience such changes from drinking coffee. Proving a causal role for coffee requires longer-term studies.