A large Finnish study published today in the European Journal of Nutrition found that habitual coffee drinkers had less total and visceral fat, more skeletal muscle mass, and healthier metabolic markers than people who drank less coffee — even when both groups had a similar BMI.
The study also revealed distinct hormonal patterns: men who drank more coffee had higher total and bioavailable testosterone, while both men and women showed lower levels of branched-chain amino acids linked to insulin resistance and type 2 diabetes risk.
Here's what the research actually found — and what it doesn't prove.
The Study at a Glance
Researchers at the University of Oulu analyzed data from 2,264 adults (age 46) enrolled in the Northern Finland Birth Cohort 1966. They examined how participants' usual coffee intake related to circulating metabolites, cardiometabolic risk markers, and sex hormone levels.
Finland is the world's highest coffee-consuming country, averaging approximately 11.8 kg (26 lbs) per person annually. That makes this cohort especially relevant for studying the long-term associations between coffee and metabolic health.
The lead author is Luca Verroest, a Doctoral Researcher at the University of Oulu. This is additional analysis from the same Northern Finland Birth Cohort that Verroest and colleagues used to investigate coffee's association with testosterone and sex hormones — and the new findings reinforce and expand on those earlier results.
Less Fat, More Muscle — Despite Similar BMI
The headline finding: people who consumed more coffee tended to have lower levels of both total body fat and visceral fat (the metabolically dangerous fat stored around internal organs), along with greater skeletal muscle mass.
What makes this particularly interesting is that participants with higher and lower coffee intake had a similar BMI. In other words, coffee drinkers weren't simply thinner — they had a more favorable body composition. Less fat, more muscle, same scale weight.
For anyone using cold brew as a pre-workout, this aligns with existing research on caffeine's effects on fat oxidation and exercise performance.
Lower Branched-Chain Amino Acids: A Metabolic Win
Higher coffee consumption was associated with lower circulating concentrations of branched-chain amino acids (BCAAs) in both men and women. When chronically elevated, BCAAs have been linked to insulin resistance and a greater risk of developing type 2 diabetes.
This is consistent with previous research showing that coffee consumption is associated with reduced cardiometabolic risk. The BCAA finding adds another potential biological mechanism to explain why coffee drinkers tend to have lower rates of type 2 diabetes — a connection that earlier observational studies have flagged but not fully explained.
The Testosterone Connection
Some of the clearest differences appeared among men. Greater coffee consumption was associated with:
- A more favorable glucose-insulin profile
- Higher total and bioavailable testosterone
- Higher sex hormone-binding globulin (SHBG)
- Modestly lower free testosterone and free androgen index
The hormonal picture in women was less extensive. Higher coffee intake was mainly associated with increased SHBG and lower measures of free androgens.
As Verroest explained: "What stood out in our findings was a distinct hormonal signature that didn't disappear even after we took into account BMI and lifestyle factors, with several of these associations differing between men and women."
The researchers suggest that hormonal pathways could help explain some of the previously observed relationship between coffee consumption and metabolic health.
What This Means for Coffee Drinkers
If you already drink coffee daily — especially clean, zero-sugar cold brew — this study adds to a growing body of evidence that habitual coffee consumption is associated with favorable metabolic markers.
The key associations worth noting:
- Body composition: Less visceral fat, more skeletal muscle
- Metabolic markers: Lower BCAAs (linked to reduced insulin resistance risk)
- Hormonal profile: Higher total testosterone and SHBG in men
- Cardiometabolic health: More favorable glucose-insulin profile in men
These findings align with existing research on coffee and metabolic health, including studies on coffee's relationship with GLP-1 pathways and fat oxidation.
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Shop Bare Brew →Important Caveats: What This Study Does NOT Prove
This was an observational study, not a randomized controlled trial. It found associations between coffee intake and body composition, metabolic markers, and hormones — but it cannot prove that coffee directly caused any of these differences.
People who drink more coffee may differ from those who drink less in ways the study couldn't fully account for, even after adjusting for BMI and lifestyle factors. The researchers themselves note that additional research — including animal models and eventually human intervention studies — will be necessary before these findings can shape dietary recommendations.
It's also worth noting that all participants were 46-year-old Finnish adults from a single birth cohort. Results may not apply to other age groups or populations.
The Bigger Picture
This study adds to a growing stack of evidence linking habitual coffee consumption to favorable metabolic outcomes. From the 2026 AHA statement on coffee and heart health to research on coffee's relationship with GLP-1 and metabolic pathways, the scientific consensus continues to shift toward coffee as a net positive for most adults.
What makes these findings particularly interesting is the body composition angle. BMI alone doesn't distinguish between fat and muscle. Two people at the same BMI can have very different health profiles depending on their ratio of visceral fat to lean mass. This study suggests coffee drinkers may sit on the favorable side of that ratio.
If you're optimizing your caffeine intake around your health and performance goals, the type of coffee matters too. A clean caffeine source — without added sugar, artificial sweeteners, or synthetic additives — ensures you're getting the benefits of coffee's bioactive compounds without the metabolic downsides of processed energy drinks.
Study Details
Full citation: Verroest, L., Jokelainen, J., Choudhary, S., Walkowiak, J., Karhu, T., Palaniswamy, S., Auvinen, J., Jarvelin, M-R., Herzig, K-H., & Raza, G.S. (2026). Associations of habitual coffee intake with testosterone and cardiometabolic markers: the Northern Finland Birth Cohort 1966 study. European Journal of Nutrition, 65(5). DOI: 10.1007/s00394-026-04038-z
Coverage: Science Daily — Coffee drinkers have less fat, more muscle, and surprising hormone differences
Frequently Asked Questions
Does coffee increase testosterone?
This observational study found that men who drank more coffee had higher total and bioavailable testosterone. However, the study cannot prove that coffee directly increases testosterone — only that an association exists. Free testosterone and the free androgen index were actually modestly lower in higher coffee consumers. More research, including controlled trials, is needed.
Can coffee help you lose fat and build muscle?
The Finnish study found that coffee drinkers had less total and visceral body fat and more skeletal muscle mass than people who drank less coffee, even at similar BMIs. This is consistent with earlier research on caffeine and fat oxidation. However, this was observational — drinking coffee alone isn't a substitute for exercise and proper nutrition.
How much coffee did people in the study drink?
The study examined habitual coffee intake among 2,264 Finnish adults aged 46. Finland is the world's highest coffee-consuming country, averaging about 11.8 kg (26 lbs) of coffee per person per year. The study looked at varying levels of consumption and their associated metabolic and hormonal markers.
Is cold brew coffee better for body composition than regular coffee?
This study did not compare brewing methods. The metabolic benefits were associated with habitual coffee intake generally. That said, cold brew offers some advantages: it's naturally smoother, lower in acidity, and when consumed without added sugar — like Bare Brew's two-ingredient formula — provides clean caffeine without the caloric load of sweetened coffee drinks.
What are branched-chain amino acids, and why do they matter?
Branched-chain amino acids (BCAAs — leucine, isoleucine, and valine) are essential amino acids. While they're important for muscle protein synthesis, chronically elevated circulating BCAA levels have been associated with insulin resistance and increased type 2 diabetes risk. This study found that higher coffee intake was linked to lower circulating BCAA levels in both men and women.
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