1.
Subacute Ingestion of Caffeine and Oolong Tea Increases Fat Oxidation without Affecting Energy Expenditure and Sleep Architecture: A Randomized, Placebo-Controlled, Double-Blinded Cross-Over Trial.
Zhang, S, Takano, J, Murayama, N, Tominaga, M, Abe, T, Park, I, Seol, J, Ishihara, A, Tanaka, Y, Yajima, K, et al
Nutrients. 2020;(12)
Abstract
Ingesting oolong tea or caffeine acutely increases energy expenditure, and oolong tea, but not caffeine, stimulates fat oxidation. The acute effects of caffeine, such as increased heart rate and interference with sleep, diminish over 1-4 days, known as caffeine tolerance. During each 14-day session of the present study, 12 non-obese males consumed oolong tea (100 mg caffeine, 21.4 mg gallic acid, 97 mg catechins and 125 mg polymerized polyphenol), caffeine (100 mg), or placebo at breakfast and lunch. On day 14 of each session, 24-h indirect calorimetry and polysomnographic sleep recording were performed. Caffeine and oolong tea increased fat oxidation by ~20% without affecting energy expenditure over 24-h. The decrease in the respiratory quotient by oolong tea was greater than that by caffeine during sleep. The effect of oolong tea on fat oxidation was salient in the post-absorptive state. These findings suggest a role of unidentified ingredients in oolong tea to stimulate fat oxidation, and this effect is partially suppressed in a postprandial state. Two weeks of caffeine or oolong tea ingestion increased fat oxidation without interfering with sleep. The effects of subacute ingestion of caffeine and oolong tea differed from the acute effects, which is a particularly important consideration regarding habitual tea consumption.
2.
Differences in the metabolic status of healthy adults with and without active brown adipose tissue.
Zhang, Q, Ye, H, Miao, Q, Zhang, Z, Wang, Y, Zhu, X, Zhang, S, Zuo, C, Zhang, Z, Huang, Z, et al
Wiener klinische Wochenschrift. 2013;(21-22):687-95
Abstract
BACKGROUND Previous studies have proven the existence of active brown adipose tissue (BAT) in adults; however, its effect on systematic metabolism remains unclear. AIM: The current study was designed to investigate the differences in the metabolic profiles of healthy adults with and without active BAT using positron emission tomography-computed tomography (PET-CT) scans in the un-stimulated state. METHODS A cross-sectional analysis was performed to assess the health of adults using PET-CT whole-body scans at Huashan Hospital Medical Centre between November 2009 and May 2010. A total of 62 healthy adults with active BAT were enrolled in the BAT-positive group. For each positive subject, a same-gender individual who underwent PET-CT the same day and who had no detectable BAT was chosen as the negative control. Body composition was measured, and blood samples were collected for assays of metabolic profiles and other biomarkers. RESULTS In both the male and female groups, BAT-positive individuals were younger and had lower body mass indexes, fasting insulin, insulin resistance, and leptin, but a greater level of high-density lipoprotein cholesterol compared with the negative controls. In the male group, body fat content and levels of tumor necrosis factor-α were significantly lower in the BAT-positive than in the negative control group. CONCLUSIONS The healthy adults with active BAT in an un-stimulated state had favorable metabolic profiles suggesting that active BAT may be a potential target for preventing and treating obesity and other metabolic disorders.