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

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.

Metabolic flexibility during sleep

“…Subjects took breakfast (7:00, 8:00 or 9:00), lunch (12:00, 12:30 or 13:00), and dinner (18:00), and slept for 7 or 8 h from 23:00 (grey bars). Because of unequal duration of sleeping period, the 8th hour of sleep in one experiment was not included for statistical analysis 9 . Mean ± SE of RQ, energy expenditure, carbohydrate oxidation and fat oxidation for 23 h common to all data sets were shown for younger (black lines) and older (grey lines) group.…”

“…It has been assumed that RQ progressively decreases during sleep 4 . However, an improved time resolution of the whole-room indirect calorimetry revealed a seemingly counterintuitive finding that RQ reaches its nadir, and then re-ascends after midnight 8,9 . The U-shaped time course of the RQ during sleep suggests that sleeping energy metabolism does not simply reflect a transition of the nutritional state from postprandial to postabsorptive 8 .…”

“…Time course of energy metabolism in two age groups of 10 years apart. In addition to 41 men without obesity assessed for metabolically flexible and inflexible subgroups in a previous section [19][20][21][22] , another 12 male subjects aged 37.1 ± 4.3 years (range 20-56) without obesity 9 were incorporated for statistical analysis. Total of 53 men were divided based on their age; under 25 years old (n = 27, age 22.5 ± 0.2 years, body weight 67.2 ± 1.7 kg, BMI 22.2 ± 0.4 kg/m 2 , body fat % 16.2 ± 0.8) and 25 years or more (n = 26, 32.5 ± 2.0 years, 65.0 ± 1.9 kg, 21.9 ± 0.3 kg/m 2 , 16.2 ± 0.7%).…”

The Rapid Non-Destructive Detection of Adulteration and Its Degree of Tieguanyin by Fluorescence Hyperspectral Technology

“…In the tea market, the problems of tea adulteration, low-quality tea that passes as high-grade tea, and old tea that passes as new tea, also occur from time to time [7]. Tieguanyin contains the highest amino acids, vitamins, minerals, tea polyphenols, and alkaloids [8], which has the most nutritional and pharmacodynamic ingredients compared with other oolong teas, and its price is higher than other oolong teas. Pushed by high economic profits, Tieguanyin adulteration happens occasionally in the market.…”

Effect of Dietary Strategies on Respiratory Quotient and Its Association with Clinical Parameters and Organ Fat Loss: A Randomized Controlled Trial

“…However, there is little evidence linking changes in RQ to diet type as a whole, as opposed to individual macronutrients [ 23 , 24 , 25 ]. Tea has been found to affect RQ differently along daily hours and to reduce RQ after sleeping and fasting but not immediately after tea consumption [ 26 ]. In a fasting state, a higher RQ has been associated with higher weight gain and fat storage [ 22 , 27 ], contrarily to an increase in RQ following weight loss, in subjects with previous obesity [ 28 ].…”