Whether caffeine (CAF) increases fat metabolism remains debatable. Using systematic review coupled with meta-analysis, our aim was to determine effects of CAF on fat metabolism and the relevant factors moderating this effect. Electronic databases PubMed, SPORTDiscus, and Web of Science were searched using the following string: CAF AND (fat OR lipid) AND (metabolism OR oxidation). A meta-analytic approach aggregated data from 94 studies examining CAF’s effect on fat metabolism assessed by different biomarkers. The overall effect size (ES) was 0.39 (95% confidence interval [CI] [0.30, 0.47], p < .001), indicating a small effect of CAF to increase fat metabolism; however, ES was significantly higher (p < .001) based on blood biomarkers (e.g., free fatty acids, glycerol) (ES = 0.55, 95% CI [0.43, 0.67]) versus expired gas analysis (respiratory exchange ratio, calculated fat oxidation) (ES = 0.26, 95% CI [0.16, 0.37]), although both were greater than zero. Fat metabolism increased to a greater extent (p = .02) during rest (ES = 0.51, 95% CI [0.41, 0.62]) versus exercise (ES = 0.35, 95% CI [0.26, 0.44]) across all studies, although ES was not different for studies reporting both conditions (ES = 0.49 and 0.44, respectively). There were no subgroup differences based on participants’ fitness level, sex, or CAF dosage. CAF ingestion increases fat metabolism but is more consistent with blood biomarkers versus whole-body gas exchange measures. CAF has a small effect during rest across all studies, although similar to exercise when compared within the same study. CAF dosage did not moderate this effect.

咖啡因 (CAF) 是否会增加脂肪代谢仍有争议。使用系统回顾和荟萃分析，我们的目的是确定 CAF 对脂肪代谢的影响以及调节这种影响的相关因素。使用以下字符串搜索电子数据库 PubMed、SPORTDiscus 和 Web of Science：CAF AND（脂肪或脂质）AND（代谢或氧化）。一种荟萃分析方法汇总了 94 项研究的数据，这些研究检查了 CAF 对不同生物标志物评估的脂肪代谢的影响。总体效应大小 (ES) 为 0.39（95% 置信区间 [CI] [0.30, 0.47]，p  < .001），表明 CAF 对增加脂肪代谢的影响很小；然而，ES 明显更高（p < .001) 基于血液生物标志物（例如，游离脂肪酸、甘油）（ES = 0.55，95% CI [0.43，0.67]）与呼出气体分析（呼吸交换率，计算的脂肪氧化）（ES = 0.26，95 % CI [0.16, 0.37])，尽管两者都大于零。脂肪代谢增加到更大程度（p = .02) 在休息期间 (ES = 0.51, 95% CI [0.41, 0.62]) 与运动期间 (ES = 0.35, 95% CI [0.26, 0.44]) 在所有研究中，尽管 ES 在报告两种情况的研究中没有不同（ES 分别为 0.49 和 0.44）。根据参与者的健康水平、性别或 CAF 剂量，没有亚组差异。摄入 CAF 会增加脂肪代谢，但与血液生物标志物相比全身气体交换指标更一致。在所有研究中，CAF 在休息期间的影响很小，尽管在同一研究中进行比较时类似于运动。CAF 剂量没有减轻这种影响。