© Cihan Yüce
September 17, 2026
Nils Behrens
Coffee has long been linked to a range of health effects. Now, a new Finnish study has found that people with high coffee consumption had less belly fat and more muscle mass. Health expert Nils Behrens explains what these findings really tell us.
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2,264 people, all exactly 46 years old: for a current analysis of the Northern Finland Birth Cohort 1966, participants were divided according to their daily coffee consumption. 296 individuals drank one to two cups per day, 822 drank three to four, and 1,076 drank at least five. A further 70 drank no coffee at all.
BMI, waist circumference, and waist-to-hip ratio were comparable across the groups. A different picture emerged, however, when body composition was measured by bioimpedance: people in the highest coffee consumption group had, on average, less total and visceral fat as well as greater skeletal muscle mass.
What makes this interesting is not only the possible connection with coffee. The study also reveals how little body weight alone can tell us about a person's metabolic health.
BMI works like a luggage scale. It tells you how heavy your bag is — but not what's inside it. Two suitcases can each weigh 20 kilograms: one packed with sunscreen and cosmetics, the other with valuable clothing for the holiday.
In the same way, two people with an identical BMI can have a completely different distribution of fat and muscle. This becomes increasingly important with age: visceral fat accumulates around the internal organs and is associated with insulin resistance and cardiometabolic disease. Skeletal muscle, on the other hand, stabilizes glucose metabolism and serves as an important physical reserve.
For your longevity, what matters is not only whether your weight stays constant. Someone who loses muscle mass after the age of 40 while simultaneously accumulating belly fat can maintain the same BMI for years — even as their risk profile worsens.
Nils Behrens is the host of the health podcast HEALTHWISE and Strategic Brand Partner of Sunday Natural. Previously, he spent over 12 years as Chief Marketing Officer and was the face of the Lanserhof Group and host of the successful Forever Young podcast. In more than 350 expert interviews, he explored pathways to a longer and fitter life.
The researchers also analyzed numerous metabolic markers. Higher coffee consumption was associated with lower blood concentrations of several branched-chain amino acids, known as BCAAs, in both men and women. These amino acids are essential for life; however, persistently elevated blood levels can indicate impaired metabolic processing and have been linked to insulin resistance and type 2 diabetes.
In men, higher coffee consumption was additionally correlated with lower fasting insulin levels, a lower insulin response in the glucose tolerance test, and higher calculated insulin sensitivity. In women, the associations were weaker.
The observed correlations were, however, mostly small. Some lipid metabolism values and the calculated cardiovascular risk score were also less favorable among heavier coffee drinkers. A single positive headline therefore does not fully capture the overall picture.
In men, each additional daily cup was associated with higher values for total testosterone, bioavailable testosterone, and the transport protein SHBG in statistically adjusted models. At the same time, calculated free testosterone and the free androgen index were lower.
This is not a simple "testosterone boost." A higher total value does not automatically mean that more active testosterone is available in the body. The study describes a hormonal pattern at the population level — not a proven effect on strength, performance, or libido.
In women, there was no significant association with total or bioavailable testosterone. No general statement about hormonal benefits for women can therefore be drawn from this study.
The study's greatest limitation is its cross-sectional design. Coffee consumption, body composition, and laboratory values were all assessed at the same point in time. This makes it possible to show that certain characteristics occur together, but it does not prove that coffee caused them.
People who drink five or more cups a day may differ from those who drink little coffee in many other ways. The high-consumption group, for instance, contained more smokers and fewer individuals with a university degree. Diet, stress, sleep, work schedules, and health factors not yet captured could all have influenced the results.
Although the hormonal calculations were adjusted for factors including BMI, education, smoking, physical activity, and alcohol consumption, statistical correction can never fully rule out unknown confounding variables.
It also remains unclear which component of coffee might theoretically be responsible. Caffeine briefly influences energy expenditure and fat oxidation, but coffee also contains polyphenols and numerous other bioactive substances. Alternatively, the beverage may simply be a visible marker of a particular lifestyle.
The number "five" is less precise than it sounds. The highest group started at a minimum of five cups with no defined upper limit, cup size was not standardized, and no information was collected on beans, roast, or additives such as milk or sugar. The vast majority of the individuals studied drank filter coffee.
Most importantly, it was never tested whether increasing consumption to five cups actually causes people to lose fat or build muscle. An observed association must therefore never be turned into a dosage recommendation.
The European Food Safety Authority considers up to 400 milligrams of caffeine per day to be generally safe for healthy adults. Depending on cup size and brew strength, five cups can exceed this amount. During pregnancy, a limit of 200 milligrams applies. Even around 100 milligrams consumed close to bedtime can disrupt sleep in sensitive individuals.
This is where the longevity conflict lies: a potential metabolic benefit would count for little if additional coffee worsens your sleep, causes palpitations, or has an unfavorable effect on blood pressure. If you have relevant pre-existing conditions or are taking medication, you should discuss a tolerable amount with a doctor.
The study gives no reason to reluctantly drink more coffee. It does, however, give a good reason not to assess health exclusively through body weight.
If you tolerate coffee well, it can be part of a healthy lifestyle. Even more important are regular strength training, sufficient physical activity, adequate protein intake, and restorative sleep. Beyond your weight, pay attention to your waist circumference, your strength, and your physical performance.
BMI measures mass, but not its quality. In the Finnish data, coffee was a notably striking marker along the axis on which less visceral fat and more muscle mass stood in opposition to each other. Whether it actually drives this shift is something that controlled long-term studies have yet to demonstrate.
So don't chase a spectacular cup count. Protect your muscles, your insulin sensitivity, and your sleep — these factors are likely to matter far more for your healthy years of life than a fifth cup of coffee.
All columns by Nils Behrens on premiummedicalcircle.com can be found here!
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