A study published by Johns Hopkins University analyzed what happens to the body when you drink coffee without sugar.
A Johns Hopkins University study, published in Nature Neuroscience, analyzed how black coffee consumption impacts the body. Researchers found signals linking this beverage to cellular protection mechanisms and changes in neuronal activity. The evidence suggests effects beyond the simple stimulation provided by caffeine.
What happens to the body when you drink coffee without sugar?

Scientists detected specific effects in the hippocampus, the brain region associated with memory and learning. According to the study, regular consumption of unsweetened coffee enhances connectivity between neurons and can improve cognitive ability, provided it is consumed in moderation. These changes would improve attention and memory consolidation.
Metabolically, the study points to two mechanisms by which unsweetened coffee can help control weight: increased thermogenesis and a higher basal metabolic rate. By increasing energy expenditure and accelerating nutrient processing, coffee may contribute to weight loss strategies when combined with diet and exercise.
The benefits and risks of coffee according to experts
Coffee beans contain concentrated antioxidants that reduce oxidative damage and help preserve tissues. The analysis also suggests a protective effect on circulation: moderate consumption is associated with a lower risk of arterial blockage and heart problems. These properties make black coffee a potential ally for vascular health, according to the authors.
A lesser-known finding points to benefits for oral health: unsweetened coffee may help reduce the proliferation of bacteria linked to cavities. Experts warn, however, that adding sugar or artificial sweeteners negates this effect and contributes to enamel erosion, so the key is to drink it unsweetened.
The authors emphasize that the benefits are observed with moderate consumption and warn against excessive caffeine. Furthermore, the quality and format of the coffee (ground versus instant) can alter its chemical composition and, therefore, its effects. That’s why they recommend prioritizing variety of origin and traditional preparation whenever possible.

