Obesity as an influencing factor for the occurrence of caffeine-induced effects in women.

BECKGROUND AND AIMS: Individuals with a higher body fat percentage may have higher serum levels of caffeine and its metabolites and process caffeine more slowly than individuals with a lower body fat percentage, so the aim of this study is to compare the occurrence of positive and negative effects of caffeine in nonobese and obese women.

METHODS AND

RESULTS

One hundred and sixty women were included in the study. Body fat was determined using the mBCA 515 SECA analyzer. Participants were divided into 4 groups: nonobese caffeine, nonobese placebo, obese caffeine and obese placebo. Caffeine groups received 6 mg/kg body weight caffeine. Placebo groups received identical starch-filled capsules. One hour after ingestion and within 24 h, participants completed a caffeine-induced effect questionnaire. Caffeine intake showed statistically significant differences compared to placebo for neutral (p ≤ 0.014; Cramér's V = 0.27; 27 % increase), negative (p ≤ 0.002; Cramér's V = 0.34; 34 % increase), and positive effects (p ≤ 0.015; Cramér's V = 0.27; 27 % increase). Further analysis revealed significant associations with increased urine output (p ≤ 0.014; Cramér's V = 0.27; 27 % increase), vigor/activeness (p ≤ 0.009; Cramér's V = 0.29; 29 % increase), and headache (p ≤ 0.033; Cramér's V = 0.24; 24 % increase) 1 h post-ingestion. No significant effects were observed in the placebo group. There was no statistically significant placebo effect.

CONCLUSIONS

Obese and nonobese women show different responses to caffeine 60 min after ingesting 6 mg/kg body weight. Obese women are more likely to report adverse effects, including increased urine output, heightened vigor/activeness, and headaches, compared to nonobese women.

TRIAL REGISTRATION: ANZCTR12622000823774; June 10, 2022.