Long-term green tea extract supplementation does not affect fat absorption, resting energy expenditure, and body composition in adults.

BACKGROUND: Green tea (GT) extract may play a role in body weight regulation. Suggested mechanisms are decreased fat absorption and increased energy expenditure. OBJECTIVE: We examined whether GT supplementation for 12 wk has beneficial effects on weight control via a reduction in dietary lipid absorption as well as an increase in resting energy expenditure (REE). METHODS: Sixty Caucasian men and women [BMI (in kg/m²): 18-25 or >25; age: 18-50 y] were included in a randomized placebo-controlled study in which fecal energy content (FEC), fecal fat content (FFC), resting energy expenditure, respiratory quotient (RQ), body composition, and physical activity were measured twice (baseline vs. week 12). For 12 wk, subjects consumed either GT (>0.56 g/d epigallocatechin gallate + 0.28-0.45 g/d caffeine) or placebo capsules. Before the measurements, subjects recorded energy intake for 4 consecutive days and collected feces for 3 consecutive days. RESULTS: No significant differences between groups and no significant changes over time were observed for the measured variables. Overall means ± SDs were 7.2 ± 3.8 g/d, 6.1 ± 1.2 MJ/d, 67.3 ± 14.3 kg, and 29.8 ± 8.6% for FFC, REE, body weight, and body fat percentage, respectively. CONCLUSION: GT supplementation for 12 wk in 60 men and women did not have a significant effect on FEC, FFC, REE, RQ, and body composition.

The role of catechol-O-methyl transferase Val(108/158)Met polymorphism (rs4680) in the effect of green tea on resting energy expenditure and fat oxidation: a pilot study.

INTRODUCTION: Green tea(GT) is able to increase energy expenditure(EE) and fat oxidation(FATox) via inhibition of catechol-O-methyl transferase(COMT) by catechins. However, this does not always appear unanimously because of large inter-individual variability. This may be explained by different alleles of the functional COMT Val108/158Met polymorphism that are associated with COMT enzyme activity; high-activity enzyme, COMT(H)(Val/Val genotype), and low-activity COMT(L)(Met/Met genotype). METHODS: Fourteen Caucasian subjects (BMI: 22.2±2.3 kg/m2, age: 21.4±2.2 years) of whom 7 with the COMT(H)-genotype and 7 with the COMT(L)-genotype were included in a randomized, cross-over study in which EE and substrate oxidation were measured with a ventilated-hood system after decaffeinated GT and placebo(PL) consumption. RESULTS: At baseline, EE, RQ, FATox and carbohydrate oxidation(CHOox) did not differ between groups. Significant interactions were observed between COMT genotypes and treatment for RQ, FATox and CHOox (p<0.05). After GT vs. PL, EE(GT: 62.2 vs. PL: 35.4 kJ.3.5 hrs; p<0.01), RQ(GT: 0.80 vs. PL: 0.83; p<0.01), FATox(GT: 18.3 vs. PL: 15.3 g/d; p<0.001) and CHOox(GT: 18.5 vs. PL: 24.3 g/d; p<0.001) were significantly different for subjects carrying the COMT(H) genotype, but not for subjects carrying the COMT(L) genotype (EE, GT: 60.3 vs. PL: 51.7 kJ.3.5 hrs; NS), (RQ, GT: 0.81 vs. PL: 0.81; NS), (FATox, GT: 17.3 vs. PL: 17.0 g/d; NS), (CHOox, GT: 22.1 vs. PL: 21.4 g/d; NS). CONCLUSION: Subjects carrying the COMT(H) genotype increased energy expenditure and fat-oxidation upon ingestion of green tea catechins vs, placebo, whereas COMT(L) genotype carriers reacted similarly to GT and PL ingestion. The differences in responses were due to the different responses on PL ingestion, but similar responses to GT ingestion, pointing to different mechanisms. The different alleles of the functional COMT Val108/158Met polymorphism appear to play a role in the inter-individual variability for EE and FATox after GT treatment. TRIAL REGISTRATION: Nederlands Trial register NTR1918.

Acute effects of capsaicin on energy expenditure and fat oxidation in negative energy balance.

BACKGROUND: Addition of capsaicin (CAPS) to the diet has been shown to increase energy expenditure; therefore capsaicin is an interesting target for anti-obesity therapy. AIM: We investigated the 24 h effects of CAPS on energy expenditure, substrate oxidation and blood pressure during 25% negative energy balance. METHODS: Subjects underwent four 36 h sessions in a respiration chamber for measurements of energy expenditure, substrate oxidation and blood pressure. They received 100% or 75% of their daily energy requirements in the conditions '100%CAPS', '100%Control', '75%CAPS' and '75%Control'. CAPS was given at a dose of 2.56 mg (1.03 g of red chili pepper, 39,050 Scoville heat units (SHU)) with every meal. RESULTS: An induced negative energy balance of 25% was effectively a 20.5% negative energy balance due to adapting mechanisms. Diet-induced thermogenesis (DIT) and resting energy expenditure (REE) at 75%CAPS did not differ from DIT and REE at 100%Control, while at 75%Control these tended to be or were lower than at 100%Control (p = 0.05 and p = 0.02 respectively). Sleeping metabolic rate (SMR) at 75%CAPS did not differ from SMR at 100%CAPS, while SMR at 75%Control was lower than at 100%CAPS (p = 0.04). Fat oxidation at 75%CAPS was higher than at 100%Control (p = 0.03), while with 75%Control it did not differ from 100%Control. Respiratory quotient (RQ) was more decreased at 75%CAPS (p = 0.04) than at 75%Control (p = 0.05) when compared with 100%Control. Blood pressure did not differ between the four conditions. CONCLUSION: In an effectively 20.5% negative energy balance, consumption of 2.56 mg capsaicin per meal supports negative energy balance by counteracting the unfavorable negative energy balance effect of decrease in components of energy expenditure. Moreover, consumption of 2.56 mg capsaicin per meal promotes fat oxidation in negative energy balance and does not increase blood pressure significantly. TRIAL REGISTRATION: Nederlands Trial Register; registration number NTR2944.

Effects of sleep fragmentation in healthy men on energy expenditure, substrate oxidation, physical activity, and exhaustion measured over 48 h in a respiratory chamber.

BACKGROUND: Epidemiologic studies show an inverse or U-shaped relation between sleep duration and BMI. Decreases in total energy expenditure (TEE) and physical activity have been suggested to be contributing factors. OBJECTIVE: The objective was to assess the effect of sleep fragmentation on energy metabolism and energy balance in healthy men. DESIGN: Fifteen healthy male subjects [mean ± SD BMI (in kg/m(2)): 24.1 ± 1.9; age: 23.7 ± 3.5 y] were included in a randomized crossover study in which energy expenditure, substrate oxidation, and physical activity (by radar) were measured twice for 48 h in a respiration chamber while subjects were monitored by electroencephalography to determine slow-wave sleep (SWS), rapid eye movement (REM) sleep, and total sleeping time (TST). During 2 nights, sleep (2330-0730 h) was either fragmented or nonfragmented. RESULTS: Fragmented sleep led to reductions in TST, SWS, and REM sleep (P < 0.001). TEE did not differ (9.96 ± 0.17 compared with 9.83 ± 0.13 MJ/d, NS) between the sleep groups, nor did the components of energy expenditure, with the exception of activity-induced energy expenditure (AEE; 1.63 ± 0.15 compared with 1.42 ± 0.13 MJ/d for fragmented and nonfragmented sleep, respectively; P < 0.05). Physical activity, exhaustion, sleepiness, respiratory quotient (RQ), and carbohydrate oxidation were elevated in comparison with nonfragmented sleep [physical activity counts: 2371 ± 118 compared with 2204 ± 124 counts/d, P < 0.02; exhaustion: 40.1 ± 3.8 compared with 21.8 ± 2.4 mm (by using a visual analog scale; VAS), P < 0.001; sleepiness: 47.4 ± 4.2 compared with 33.9 ± 4.6 mm (VAS), P < 0.001; RQ: 0.94 ± 0.04 compared with 0.91 ± 0.03, P < 0.05; and carbohydrate oxidation: 346.3 ± 23.8 compared with 323.7 ± 22.5 g/d, P < 0.05], whereas fat oxidation was reduced (29.1 ± 9.1 compared with 61.0 ± 6.6 g/d, P < 0.01). CONCLUSIONS: Fragmented compared with nonfragmented sleep induced reductions in the most important sleep phases, which coincided with elevated AEE, physical activity, exhaustion, and sleepiness. RQ and carbohydrate oxidation increased and fat oxidation decreased, which may predispose to overweight. This trial is registered at www.who.int/ictrp and www.trialregister.nl as NTR1919.