This study investigates how caffeinated coffee, decaffeinated coffee, and water affect body composition, as measured by BIA. Participants were divided into three groups, consuming their respective beverages, with measurements taken over a 120-minute period. The study aimed to determine if caffeine or fluid intake is the primary driver of changes in body composition parameters.

This study aims to address these gaps by examining how caffeinated coffee, decaffeinated coffee, and water influence BIA measurements at multiple intervals post-consumption (baseline, 30, 60, 90, and 120 minutes). By incorporating a controlled study design with separate water-only and caffeine-free groups, this methodology overcomes the limitations of previous studies that lacked comprehensive control conditions. By determining whether caffeine or fluid volume primarily drives changes in BIA parameters and identifying the timing of these effects, this research seeks to improve the understanding of external factors affecting BIA, providing valuable insights for accurate body composition assessments.

Participants were divided into three groups based on their average daily caffeine consumption: caffeinated coffee, decaffeinated coffee, and water.

To standardize caffeine and fluid intake, filter coffee was chosen for its consistency in caffeine content and fluid volume. Both caffeinated and decaffeinated Arabic coffee were prepared using 11 g of coffee per 200 ml of water. The coffee was weighed using a precision balance and brewed with a filter coffee machine to ensure uniform preparation.

Participants were instructed to adhere to the following restrictions prior to the analysis day: a 12-hour fast, avoidance of excessive fluids, abstinence from caffeine-containing beverages, no showering or sauna use, no alcohol consumption for 48 hours, and no heavy exercise for 4-12 hours before the measurement. These restrictions minimized potential confounding effects on hydration or metabolic state, ensuring reliable BIA measurements.

The first BIA measurements were taken before any beverage consumption. Subsequently, participants consumed 200 ml of caffeinated coffee, decaffeinated coffee, or water, depending on their group. BIA measurements were repeated at 30, 60, 90, and 120 minutes post-consumption.

Inclusion Criteria:

• Healthy adults aged ≥18 years.
• BMI between 18.5 and 29.9 kg/m².
• Regular coffee consumers.
• Participants providing written informed consent.

Exclusion Criteria:

• Individuals on medication or hormone therapy within the last 6 months.
• Medical conditions affecting caffeine metabolism (e.g., allergies or intolerances).
• Chronic or acute diseases.
• Significant appetite or eating disturbances in the past 6 months.
• Participants menstruating on the day of analysis.