Influence of age on the thermic response to caffeine in women

Coffee and brain health: An introductory overview

Introduction to the "Impact of Coffee on Brain Health" explores the multifaceted relationship between coffee consumption and brain function. The chapter begins by highlighting coffee's global popularity and cultural significance, setting the stage for an in-depth exploration of its effects on brain health. It describes the intricate components of coffee, including caffeine, antioxidants, and polyphenols, elucidating their physiological and medicinal roles in promoting cognitive function and neuroprotection. While moderate coffee consumption offers potential benefits such as enhanced cognitive performance and mood regulation, excessive intake can pose risks such as insomnia and medication interactions. Research studies provide robust evidence supporting coffee's neuroprotective effects, while practical implications offer recommendations for optimizing consumption and minimizing risks. By embracing a personalized approach to coffee consumption and staying informed about its potential impacts, individuals can harness its benefits for brain health and overall well-being.

Appraisal of the causal effect of plasma caffeine on adiposity, type 2 diabetes, and cardiovascular disease: two sample mendelian randomisation study

Objective

To investigate the potential causal effects of long term plasma caffeine concentrations on adiposity, type 2 diabetes, and major cardiovascular diseases.

Design

Two sample mendelian randomisation study.

Setting

Genome-wide association study summary data for associations of two single nucleotide polymorphisms associated with plasma caffeine at the genome-wide significance threshold (rs2472297 near the CYP1A2 gene and rs4410790 near the AHR gene) and their association with the outcomes.

Participants

Primarily individuals of European ancestry participating in cohorts contributing to genome-wide association study consortia.

Main outcome measures

Outcomes studied were body mass index, whole body fat mass, whole body fat-free mass, type 2 diabetes, ischaemic heart disease, atrial fibrillation, heart failure, and stroke.

Results

Higher genetically predicted plasma caffeine concentrations were associated with lower body mass index (beta -0.08 standard deviation (SD) (95% confidence interval -0.10 to -0.06), where 1 SD equals about 4.8 kg/m² in body mass index, for every standard deviation increase in plasma caffeine) and whole body fat mass (beta -0.06 SD (-0.08 to -0.04), 1 SD equals about 9.5 kg; P<0.001) but not fat-free mass (beta -0.01 SD (-0.02 to -0.00), 1 SD equals about 11.5 kg; P=0.17). Higher genetically predicted plasma caffeine concentrations were associated with a lower risk of type 2 diabetes in two consortia (FinnGen and DIAMANTE), with a combined odds ratio of 0.81 ((95% confidence interval 0.74 to 0.89); P<0.001). Approximately half (43%; 95% confidence interval 30% to 61%) of the effect of caffeine on type 2 diabetes was estimated to be mediated through body mass index reduction. No strong associations were reported between genetically predicted plasma caffeine concentrations and a risk of any of the studied cardiovascular diseases.

Conclusions

Higher plasma caffeine concentrations might reduce adiposity and risk of type 2 diabetes. Further clinical study is warranted to investigate the translational potential of these findings towards reducing the burden of metabolic disease.

Coffee Consumption and the Risk of Obesity in Korean Women

Instant coffee mixes that contain sugar and non-dairy creamer account for 80-90% of the total coffee market in Korea. The objective of this study was to investigate the relationship between coffee consumption and obesity in Korean women. We included 5995 women who participated in a health screening examination at the Korean National Cancer Center between 2007 and 2016. Daily coffee consumption and the use of sugar and creamer in coffee was evaluated using a 106-item food frequency questionnaire. Obesity was assessed by body mass index (BMI), and abdominal obesity was assessed by waist circumference (WC). A multiple logistic regression model was used to calculate the odds ratio (OR) of obesity according to coffee consumption. After multivariate adjustment, high coffee consumption was positively associated with obesity as measured by BMI (≥3 cups vs. no drinks, OR = 2.52; 95% confidence interval (CI) = 1.91-3.34; p for the trend < 0.001) and abdominal obesity as measured by WC (≥3 cups vs. no drinks, OR = 2.11; 95% CI = 1.59-2.79; p for the trend < 0.001). The positive association between daily coffee consumption and obesity prevalence was not altered by menopause. The amount of coffee with additives consumed per day by Korean women was positively correlated with the prevalence of obesity, but causation cannot be determined due to the cross-sectional nature of the study design. The mechanism underlying the observed relationship is yet to be elucidated.

A minireview of effects of green tea on energy expenditure

In recent years, individuals have begun to tend more frequently to some natural and herbal products to be used alone or as a combination with diet and exercise for ensuring the weight loss. Green tea is the leading one of these products. In some studies, it is reported that the green tea causes an increase in thermogenesis and substrate with fat oxidation by affecting on the sympathetic nervous system. It is reported that green tea has two main components that are associated with energy expenditure. One of them is caffeine and the other is catechin content. Each of these two components has an impact on energy mechanism separately. In this minireview article, mechanisms of action and effects of caffeine and catechin, which are found in green tea composition, on energy expenditure are assessed.

Effects of Chinese Green Tea on Weight, and Hormonal and Biochemical Profiles in Obese Patients With Polycystic Ovary Syndrome—A Randomized Placebo-Controlled Trial

OBJECTIVES

To study the effects of green tea on body weight, and biochemical and hormonal profiles in obese Chinese women with polycystic ovary syndrome (PCOS).

METHODS

Thirty-four obese Chinese women with PCOS were randomized into either treatment with green tea capsules or placebo for 3 months. The anthropometric measurements, and biochemical and hormonal profiles before and after treatment in each group were compared.

RESULTS

The body weight of the green tea group decreased by a nonsignificant 2.4% after treatment; whereas the body weight, body mass index (BMI), and body fat content of the control group were significantly higher after 3 months. There were no differences in any of the hormone levels measured in either group. The biochemical profiles of the two groups were also similar except that there was a small but significant rise in the triglyceride level in the green tea group. Fewer patients in the green tea group remained amenorrhoeic, but this was not significantly different from the control group.

CONCLUSIONS

Green tea supplementation did not significantly reduce body weight in obese women with PCOS, nor did it alter the glucose or lipid metabolism.

Performance Enhancing Diets and the PRISE Protocol to Optimize Athletic Performance

The training regimens of modern-day athletes have evolved from the sole emphasis on a single fitness component (e.g., endurance athlete or resistance/strength athlete) to an integrative, multimode approach encompassing all four of the major fitness components: resistance (R), interval sprints (I), stretching (S), and endurance (E) training. Athletes rarely, if ever, focus their training on only one mode of exercise but instead routinely engage in a multimode training program. In addition, timed-daily protein (P) intake has become a hallmark for all athletes. Recent studies, including from our laboratory, have validated the effectiveness of this multimode paradigm (RISE) and protein-feeding regimen, which we have collectively termed PRISE. Unfortunately, sports nutrition recommendations and guidelines have lagged behind the PRISE integrative nutrition and training model and therefore limit an athletes' ability to succeed. Thus, it is the purpose of this review to provide a clearly defined roadmap linking specific performance enhancing diets (PEDs) with each PRISE component to facilitate optimal nourishment and ultimately optimal athletic performance.

Caffeine consumption around an exercise bout: effects on energy expenditure, energy intake, and exercise enjoyment

Combining an exercise and nutritional intervention is arguably the optimal method of creating energy imbalance for weight loss. This study sought to determine whether combining exercise and caffeine supplementation was more effective for promoting acute energy deficits and manipulations to substrate metabolism than exercise alone. Fourteen recreationally active participants (mean ± SD body mass index: 22.7 ± 2.6 kg/m2) completed a resting control trial (CON), a placebo exercise trial (EX), and a caffeine exercise trial (EX+CAF, 2 × 3 mg/kg of caffeine 90 min before and 30 min after exercise) in a randomized, double-blinded design. Trials were 4 h in duration with 1 h of rest, 1 h of cycling at ∼65% power at maximum O2 consumption or rest, and a 2-h recovery. Gas exchange, appetite perceptions, and blood samples were obtained periodically. Two hours after exercise, participants were offered an ad libitum test meal where energy and macronutrient intake were recorded. EX+CAF resulted in significantly greater energy expenditure and fat oxidation compared with EX (+250 kJ; +10.4 g) and CON (+3,126 kJ; +29.7 g) (P < 0.05). A trend for reduced energy and fat intake compared with CON (-718 kJ; -8 g) (P = 0.055) was observed. Consequently, EX+CAF created a greater energy deficit (P < 0.05). Caffeine also led to exercise being perceived as less difficult and more enjoyable (P < 0.05). Combining caffeine with exercise creates a greater acute energy deficit, and the implications of this protocol for weight loss or maintenance over longer periods of time in overweight/obese populations should be further investigated.

Increased protein intake and meal frequency reduces abdominal fat during energy balance and energy deficit

OBJECTIVE

Unrefined, complex carbohydrates and lean protein diets are used to combat obesity, although it's unknown whether more frequent meals may improve this response. The effects of consuming traditional (~15%) versus higher (~35%) protein intakes as three or six meals/day on abdominal fat, postprandial thermogenesis (TEM), and cardiometabolic biomarkers in overweight individuals during 28 days of energy balance (BAL) and deficit (NEG), respectively were compared.

DESIGN AND METHODS

Overweight individuals (n = 30) were randomized into three groups: two high-protein groups (35% of energy) consumed as three (HP3) or six (HP6) meals/day and one group consumed three meals/day of a traditional intake (TD3). Following a 5-day baseline control (CON), subjects consumed their respective diets throughout a 56-day intervention consisting of two, 28 day phases: a BAL followed by a NEG phase (75% of energy needs). Total body fat (BF) and abdominal BF (ABF), body weight (BW), TEM, and fasting biomarkers were assessed at the end of CON, BAL, and NEG phases.

RESULTS

BW remained stable throughout CON and BAL in all groups, whereas BF (P < 0.001) and ABF (P < 0.01) decreased in HP groups and lean body mass (LBM) and leptin increased in HP6. Following NEG, BW decreased in all groups. BF, ABF, and leptin decreased in HP groups; LBM remained higher (P < 0.05), and TEM was highest in HP6 (P < 0.05).

CONCLUSIONS

Consuming increased protein (∼35%) more frequently (6×) throughout the day decreases BF and ABF, increases LBM and TEM, and favorably affects adipokines more than current recommendations for macronutrients consumed over three meals/day in overweight individuals during both BAL and NEG.

Epigallocatechin-3-gallate and postprandial fat oxidation in overweight/obese male volunteers: a pilot study

OBJECTIVES

Drinking green tea is associated with many health benefits, including increased fat oxidation. We tested the hypothesis that epigallocatechin-3-gallate (EGCG), the main green tea catechin, increases fat oxidation in obese men.

METHODS

Ten healthy overweight/obese males (body mass index 31.3+/-0.8 kg/m(2)) were studied in a randomized, placebo-controlled, double-blind crossover trial. Study supplements were low EGCG (300 mg), high EGCG (600 mg), caffeine (200 mg), EGCG/caffeine (300 mg/200 mg) or placebo and were taken orally for 3 days. At the third day of supplementation, O(2) consumption and CO(2) production was measured by indirect calorimetry to assess energy expenditure and fat oxidation over 4 h each after overnight fasting and after a standardized test meal.

RESULTS

Energy expenditure was not affected by any supplementation, neither after overnight fasting nor after the test meal. During the first 2 h after overnight fasting, fat oxidation increased by 7.7 (not significant, NS), 15.2 (NS), 26.3 (P<0.05 vs placebo) and 35.4% (P<0.01 vs placebo and low EGCG), for low EGCG, high EGCG, caffeine and EGCG/caffeine, respectively. During the first 2 h after the meal, the mean increase in fat oxidation was 33.3 (P<0.05 vs placebo), 20.2 (NS), 34.5 (P<0.05 vs placebo) and 49.4% (P<0.05 vs placebo) for low EGCG, high EGCG, caffeine and EGCG/caffeine, respectively.

CONCLUSIONS

Low EGCG increases postprandial fat oxidation in obese men and this to the same extent as 200 mg caffeine, whereas high EGCG does not exert this effect. Fasting fat oxidation is increased only by caffeine (with or without EGCG). There is no synergism of low EGCG and 200 mg caffeine. Energy expenditure is not affected by EGCG.

Relationship of blood pressure, behavioral mood state, and physical activity following caffeine ingestion in younger and older women

The purpose of this study was to examine the age-related differences in blood pressure, heart rate, and behavioral mood state after caffeine ingestion in younger and older women. Using a placebo-controlled, double-blind design, 10 younger (Y; 18-22 years) and 10 older (O; 50-67 years) healthy women who were moderate consumers of caffeine (self-reported mean intake: Y, 139 +/- 152 mg.day-1; O, 204 +/- 101 mg.day-1) were investigated. All volunteers were characterized for fasting plasma glucose, insulin, free-fatty acids and caffeine levels, body composition, cardiovascular fitness, physical activity, and energy intake. Before and after placebo and caffeine ingestion (5 mg.kg-1 fat-free mass; approximately 208-270 mg) test days, the following variables were measured in all subjects: plasma caffeine levels, heart rate, blood pressure, and behavioral mood state. Results showed that, following caffeine ingestion: (i) both systolic and diastolic blood pressure (SBP and DBP, respectively) increased significantly (p < 0.05) in the older women (SBP, 128.4 +/- 14.2 vs. 132.1 +/- 13.0 mm Hg (3%); DBP, 80.2 +/- 6.9 vs. 83.4 +/- 7.5 mm Hg (4%), whereas only DBP increased in the younger women (67.1 +/- 4.7 vs. 69.9 +/- 5.4 mm Hg (4.2%); p < 0.05); (ii) heart rate decreased significantly (Y, 59.2 +/- 8.7 to 53.9 +/- 10.6 beats.min-1 (p < 0.05); O, 61.9 +/- 9.2 to 59.2 +/- 8.4 beats.min-1 (p < 0.05)) in both groups; and (iii) self-reported feelings of tension and vigor increased and feelings of fatigue decreased (p < 0.05) in younger women, whereas depression decreased (p < or = 0.05) in older women. Self-reported level of physical activity was inversely related to change in DBP following caffeine ingestion in younger women. In conclusion, blood pressure response is augmented and subjective feelings of behavioral mood state are attenuated to a greater degree in older than in younger women following acute caffeine ingestion. Less physically active younger women are more vulnerable to the pressor response to caffeine than more active younger women. It should be noted that these findings are limited to moderate consumers of caffeine who abstained for 48 h prior to testing, and who ingested caffeine in pill form (approximately 240 mg).

Metabolic testing in the office

The three most commonly used metabolic tests are the Resting Metabolic Rate, Anaerobic Threshold Testing, and V.O2max. For several decades, these metabolic tests have been confined to the setting of university-based physiology laboratories and cardiopulmonary environments, i.e., metabolic carts in the intensive care units. The information gathered is used as a research and clinical tool in evaluating metabolic activity in a variety of physiological states from a body at rest, to exercise (aerobic and anaerobic), in certain medical states like illness, fed/starvation, and medicinal or supplementation affective states. Over the last decade, as technology has improved, so have the metabolic testing carts. They have become widely available for mainstream use by a variety of health care professionals. The purpose of this article is to review these three tests and how they may be useful in a medical practice.

The effects of epigallocatechin-3-gallate on thermogenesis and fat oxidation in obese men: a pilot study

OBJECTIVES

The development of obesity is characterized by an increase in adipose tissue mass and by concomitant and profound changes in almost all organ functions leading to diseases such as hypertension, diabetes mellitus and coronary heart disease. Recent data from human studies indicate that the consumption of green tea and green tea extracts may help reduce body weight, mainly body fat, by increasing postprandial thermogenesis and fat oxidation. However, human studies investigating the metabolic effects of the most predominant tea catechin, EGCG, alone are absent.

METHODS

In a randomized double blind, placebo-controlled, cross-over pilot study, six overweight men were given 300 mg EGCG/d for 2d. Fasting and postprandial changes in energy expenditure (EE) and substrate oxidation were assessed.

RESULTS

Resting EE did not differ significantly between EGCG and placebo treatments, although during the first postprandial monitoring phase, respiratory quotient (RQ) values were significantly lower with EGCG compared to the placebo.

CONCLUSIONS

These findings suggest that EGCG alone has the potential to increase fat oxidation in men and may thereby contribute to the anti-obesity effects of green tea. However, more studies with a greater sample size and a broader range of age and BMI are needed to define the optimum dose.

Metabolic responses to the acute ingestion of two commercially available carbonated beverages: A pilot study

Background

The purpose of this placebo-controlled, double-blind cross-over study was to compare the effects of two commercially available soft drinks on metabolic rate.

Methods

After giving informed consent, twenty healthy men and women were randomly assigned to ingest 12 ounces of Celsius™ and, on a separate day, 12 ounces of Diet Coke®. All subjects completed both trials using a randomized, counterbalanced design. Metabolic rate (via indirect calorimetry) and substrate oxidation (via respiratory exchange ratio) were measured at baseline (pre-ingestion) and at the end of each hour for 3 hours post-ingestion.

Results

Two-way ANOVA revealed a significant interaction (p < 0.001) between trials in metabolic rate. Scheffe post-hoc testing indicated that metabolic rate increased by 13.8% (+ 0.6 L/min, p < 0.001) 1 hr post, 14.4% (+0.63 L/min, p < 0.001) 2 hr post, and 8.5% (+0.37 L/min, p < 0.004) 3 hr post Celsius™ ingestion. In contrast, small (~4–6%) but statistically insignificant increases in metabolic rate were noted following Diet Coke^® ingestion. No differences in respiratory exchange ratio were noted between trials.

Conclusion

These preliminary findings indicate Celsius™ has thermogenic properties when ingested acutely. The effects of repeated, chronic ingestion of Celsius™ on body composition are unknown at this time.

Best Practice Methods to Apply to Measurement of Resting Metabolic Rate in Adults: A Systematic Review

Several factors may alter apparent resting metabolic rate (RMR) during measurement with indirect calorimetry. Likewise, numerous indirect calorimetry measurement protocols have been developed over the years, and the methodology employed could influence test results. As part of a larger project to determine the role of indirect calorimetry in clinical practice, a systematic review of the literature was undertaken to determine the ideal subject condition and test methodology for obtaining reliable measurement of RMR with indirect calorimetry. Food, ethanol, caffeine, and nicotine affect RMR for a variable number of hours after consumption; therefore, intake of these items must be controlled before measurement. Activities of daily living increase metabolic rate, but a short rest (< or =20 minutes) before testing is sufficient for the effect to dissipate. Moderate or vigorous physical activity has a longer carryover effect and therefore must be controlled in the hours before a measurement of RMR is attempted. Limited data were found regarding ideal ambient conditions for RMR testing. Measurement duration of 10 minutes with the first 5 minutes deleted and the remaining 5 minutes having a coefficient of variation <10% gave accurate readings of RMR. Individuals preparing for RMR measurement via indirect calorimetry should refrain from eating, consuming ethanol and nicotine, smoking, and engaging in physical activity for varying times before measurement. The test site should be physically comfortable and the individual should have 10 to 20 minutes to rest before measurement commences. A 10-minute test duration with the first 5 minutes discarded and the remaining 5 minutes having a coefficient of variation of <10% will give an accurate measure of RMR.

Coffee, tea and diabetes: the role of weight loss and caffeine

OBJECTIVE

To assess the effect of weight change on the relationship between coffee and tea consumption and diabetes risk.

DESIGN

Prospective cohort study, using data from the First National Health and Nutrition Examination Survey Epidemiologic Follow Up Study. Survival analyses were conducted using 301 selfreported cases of diabetes and eight documented diabetes deaths during an 8.4-y follow-up.

SUBJECTS

A total of 7006 subjects aged 32-88 y with no reported history of diabetes were included in the study.

RESULTS

For all subjects combined, increases in consumption of ground-caffeinated coffee and caffeine at baseline were followed by decreases in diabetes risk during follow-up. There were significant statistical interactions between age and consumption of caffeine (P=0.02) and ground-caffeinated coffee (P=0.03). Age-stratified analysis showed that the decrease in diabetes risk only applied to < or =60-y-old subjects, for whom the decrease in diabetes risk also obtained for ground-decaffeinated coffee and regular tea. The multivariate hazard ratio (HR) and 95% confidence interval for a 2 cups/day increment in the intake of ground-caffeinated coffee, ground-decaffeinated coffee and regular tea was 0.86 (0.75-0.99), 0.58 (0.34-0.99) and 0.77 (0.59-1.00), respectively. The diabetes risk was negatively related to the consumption in a dose-response manner. There were strong statistical interactions between prior weight change and beverage consumption for < or =60-y-old subjects. Further analysis revealed that the decrease in diabetes risk only applied to those who had lost weight, and that there was a positive dose-response relationship between diabetes risk and weight change. For example, the multivariate HR and 95% confidence interval for >0 vs 0 cups/day of ground-decaffeinated coffee was 0.17 (0.04-0.74), 0.52 (0.19-1.42), 0.77 (0.30-1.96) and 0.91 (0.39-2.14) for subgroups with weight change of < or =0, 0-10, 10-20 and >20 lbs, respectively. There was no significant association between diabetes risk and consumption of instant-caffeinated coffee, instant-decaffeinated coffee or herbal tea. Caffeine intake appeared to explain some, but not all, of the diabetes-risk reduction and weight change.

CONCLUSION

The negative relationship between diabetes risk and consumption of ground coffee and regular tea, observed for all NHEFS subjects, actually only applied to nonelderly adults who had previously lost weight.

Effect of cola intake on insulin resistance in moderate fat-fed weaning male rats

In recent years, the prevalence of type 2 diabetes mellitus has dramatically increased in Korea as the diet has rapidly become westernized. We determined the effect of a long-term cola intake for insulin resistance in weaning male Sprague Dawley rats consuming a moderate fat diet. Thirty male pubs born from 6 female rats were randomized into cola or water drinking groups. The rats of the cola group were freely provided with 33 energy percent fat diets and cola for 28 weeks, while the rats of the control group had the same diet with water instead of cola. The daily caloric intake did not differ between groups, while the rats in the cola group consumed more carbohydrates. However, the mean body weight of the cola group was lower than that of the control group from the second week of the study. Whole body glucose disposal rates measured by euglycemic hyperinsulinemic clamp were higher in the cola group. Compared to the control group, glycogen contents and fraction velocity of glycogen synthase of the quadriceps muscle in the cola group were higher by 39.4% and 40.3%, respectively. Uncoupling protein (UCP)-2 and GLUT 4 contents of soleus and quadriceps muscles were higher in the cola group than the control group. In conclusion, insulin action improved with increased peripheral glucose utilization in weaning male rats drinking cola, which was partly due to lower body weight. This latter was possibly as a result of increased thermogenesis in muscles.

Pharmacological approaches for the treatment of obesity

The high incidence of obesity, its multifactorial nature, the complexity and lack of knowledge of the bodyweight control system, and the scarcity of adequate therapeutics have fuelled anti-obesity drug development during a considerable number of years. Irrespective of the efforts invested by researchers and companies, few products have reached a minimum level of effectiveness, and even fewer are available in medical practice. As a consequence of anti-obesity research, our knowledge of the bodyweight control system increased but, despite this, the pharmacological approaches to the treatment of obesity have not resulted yet in effective drugs. This review provides a panoramic of the multiple different approaches developed to obtain workable drugs. These approaches, however, rely in only four main lines of action: control of energy intake, mainly through modification of appetite;control of energy expenditure, essentially through the increase of thermogenesis;control of the availability of substrates to cells and tissues through hormonal and other metabolic factors controlling the fate of the available energy substrates; andcontrol of fat reserves through modulation of lipogenesis and lipolysis in white adipose tissue. A large proportion of current research is centred on neuropeptidic control of appetite, followed by the development of drugs controlling thermogenic mechanisms and analysis of the factors controlling adipocyte growth and fat storage. The adipocyte is also a fundamental source of metabolic signals, signals that can be intercepted, modulated and used to force the brain to adjust the mass of fat with the physiological means available. The large variety of different approaches used in the search for effective anti-obesity drugs show both the deep involvement of researchers on this field and the large amount of resources devoted to this problem by pharmaceutical companies. Future trends in anti-obesity drug research follow closely the approaches outlined; however, the increasing mass of information on the molecular basis of bodyweight control and obesity will in the end prevail in our search for effective and harmless anti-obesity drugs.

Oolong tea increases metabolic rate and fat oxidation in men

According to traditional Chinese belief, oolong tea is effective in the control of body weight. Few controlled studies, however, have been conducted to measure the impact of tea on energy expenditure (EE) of humans. A randomized cross-over design was used to compare 24-h EE of 12 men consuming each of four treatments: 1) water, 2) full-strength tea (daily allotment brewed from 15 g of tea), 3) half-strength tea (brewed from 7.5 g tea) and 4) water containing 270 mg caffeine, equivalent to the concentration in the full-strength tea treatment. Subjects refrained from consuming caffeine or flavonoids for 4 d prior to the study. Tea was brewed each morning; beverages were consumed at room temperature as five 300 mL servings. Subjects received each treatment for 3 d; on the third day, EE was measured by indirect calorimetry in a room calorimeter. For the 3 d, subjects consumed a typical American diet. Energy content of the diet was tailored to each subject's needs as determined from a preliminary measure of 24-h EE by calorimetry. Relative to the water treatment, EE was significantly increased 2.9 and 3.4% for the full-strength tea and caffeinated water treatments, respectively. This increase over water alone represented an additional expenditure of 281 and 331 kJ/d for subjects treated with full-strength tea and caffeinated water, respectively. In addition, fat oxidation was significantly higher (12%) when subjects consumed the full-strength tea rather than water.