Effects of ingestion of a commercially available thermogenic dietary supplement on resting energy expenditure, mood state and cardiovascular measures
© Outlaw et al.; licensee BioMed Central Ltd. 2013
Received: 11 February 2013
Accepted: 16 April 2013
Published: 30 April 2013
Increasing metabolism is a primary focus of many commercially available dietary supplements marketed to support weight management. Caffeine (e.g. anhydrous and herbal) and green tea are key ingredients in such products, augmenting resting energy expenditure (REE) and improving reported mood states (alertness, fatigue, focus, etc.). The purpose of this study was to evaluate the effects of a thermogenic dietary supplement (DBX) on REE, respiratory exchange ratio (RER), reported measures of alertness, focus, energy, concentration, fatigue, and hunger, as well as the general safety of the product based on electrocardiogram (ECG) and hemodynamic responses in habitual caffeine consumers.
Six male and six female subjects (mean ± SD; 22.50 ± 3.22 years; 76.94 ± 14.78 kg; 22.7 ± 9.5% body fat), physically active (≥12 months), and moderate habitual caffeine consumers (<200 mg/day) received either two capsules of DBX containing 340 mg of total caffeine plus green tea extract, yerba mate extract, carnitine tartrate and other active ingredients or a placebo (PLC) in a double-blinded, crossover design. Heart rate (HR), blood pressure (BP), REE, RER and perceived mood states were measured at baseline and then hourly for four hours after ingesting either treatment.
Resting energy expenditure was significantly increased at all four time points and significant increases were determined for perceived alertness (p = 0.026) and focus (p = 0.05) at hour 1 and for energy at 1 and 2 hours after treatment for the DBX group (p = 0.008 and p = 0.017, respectively). Additionally, perceived fatigue was decreased at the hour 1 assessment (p = 0.010). No significant differences were seen between DBX and placebo for hunger, anxiety, HR, BP, ECG patterns or RER.
The results of this investigation support that the proprietary blend of this thermogenic aid is capable of increasing REE for four hours post-ingestion while supporting increased focus, alertness, and energy as well as decreasing fatigue without promoting anxiety or causing significant changes in HR, BP, or ECG measurements in habitual caffeine consumers.
KeywordsCaffeine Thermogenic Resting energy expenditure
Augmentations in overall metabolism and “fat burning” are two physiological expectations of consumers when purchasing a thermogenic dietary supplement. One of the primary reasons for taking a thermogenic aid is to support weight loss and body leaning . Many of these products found on the market, and available to the general public, contain synthetic caffeine and herbal sources (e.g. guarana, yerbe mate), green tea extract, and other purported metabolic-supporting ingredients such as carnitine and capsaicin (red pepper extract). The most researched ingredient, caffeine, has been reported to have several potential ergogenic benefits including increased energy expenditure and weight loss, decreased body fat, as well as increased performance and a potential glycogen-sparing effect [2, 3]. Green tea extract with a standardized level of catechins in combination with caffeine has been shown to significantly increase daily energy expenditure and fat oxidation over that of caffeine alone . Rudelle and associates  investigated the effects of a thermogenic drink containing green tea catechins, as well as caffeine, on energy expenditure in lean individuals. The beverage increased resting energy expenditure (REE) by 4.6% and the authors suggested that this type of beverage could be beneficial for weight loss and management. The increase in energy expenditure reported by multiple researchers [6–9] positions caffeine and green tea-containing supplements as a beneficial tool to offset the reduction in energy expenditure associated with weight loss [10–12]. In addition to affecting metabolism and favoring fat as a fuel source, many studies have shown that caffeine has an impact on alertness, fatigue, and other mood states [13–15]. After ingesting 120 mg of caffeine supplementation, greater alertness was reported for up to three hours by Mitchell and colleagues  and 40 mg of caffeine combined with 97 mg of L-theanine, the key caffeine analog in tea, showed improvements in perceived alertness and tiredness 20 and 70 minutes after ingestion in an investigation led by Giesbrecht and associates . Caffeine levels of 250 mg and 500 mg also decreased reported tiredness and increased self-reported alertness when given to nine healthy subjects . One important consideration in caffeine consumption studies is the control of habitual intake as individuals can become acclimated to caffeine, thus influencing their physiological responses to a specific dose.
Seeing these potential benefits for their consumers, supplement companies have created their own proprietary blends for weight management and body leaning supplements, as well as ergogenic aids containing caffeine. Many of these products claim to increase metabolism and “fat burning” either independently, or in conjunction with the caffeine contained in the supplement. Because of the popularity of weight management supplements, researchers have investigated different thermogenic products to determine their effectiveness. For instance, Hoffman and colleagues  determined that a commercially available product containing multiple trademarked ingredient mixtures demonstrated a trend for increased fat oxidation while also increasing heart rate (HR), systolic blood pressure (SBP) and reported levels of tension and confusion among the supplement group. Another study performed in 2009  revealed that capsaicin, an active ingredient in the DBX proprietary blend, statistically increased energy expenditure and diastolic blood pressure (DBP) after ingestion but had no influence on fat utilization. A third investigation  revealed a significant effect for REE, as well as RER and SBP over three hours when regular coffee drinkers consumed a commercial product containing roughly 400 mg total caffeine.
Based on these past studies, many thermogenic supplements are successful at increasing energy expenditure, but varying doses and combinations of ingredients may cause different cardiovascular and mood state side effects. Further product-specific research on thermogenic aids is needed to determine levels of effectiveness and safety for consumers. The purpose of this study was to evaluate the effects of a commercially available thermogenic dietary supplement on energy expenditure, reported measures of alertness, focus, energy, concentration, fatigue, and hunger, as well as the general tolerance and safety of the supplement based on ECG and hemodynamic responses when taken by healthy, active, young adults.
Six males and six females (mean ± SD; age: 22.50 ± 3.22 years; weight: 76.94 ± 14.78 kg; body fat: 22.7 ± 9.5%) volunteered for the study conducted in the Human Performance Lab (HPL) at the University of Mary Hardin-Baylor in Belton, Texas. Participants were required to be apparently healthy, physically active (regularly participating in exercise for the previous 12 months), moderate caffeine users (<200 mg/day), and were excluded from the study if they had any known metabolic disorders, were sensitive to caffeine, had a history of pulmonary disease, hypertension, liver or kidney disease, musculoskeletal or neuromuscular disease, neurological disease, autoimmune disease, or any cancers, peptic ulcers, or anemia. Taking certain medications, including those for heart, pulmonary, thyroid, anti-hyperlipidemic, hypoglycemic, anti-hypertensive, endocrinologic, psychotropic, neuromuscular, neurological, or androgenic conditions, as well as a family history of heart problems, high blood pressure, and/or stroke, and being pregnant or breastfeeding were also factors for exclusion. Trained lab assistants screened and examined participants as well as obtained a complete medical history to determine if each participant met the qualification standards. Participants reported the number of caffeinated beverages (coffee, tea, soft drink, energy drink, etc.), caffeine containing medications (NoDoz, Vivarin, etc.) and caffeine containing foods (candy, chocolate ice cream, etc.) as well as the serving size (8 oz., 5 oz., etc.) of each reported caffeinated product they consumed per week on average. Average caffeine consumption was determined to be 176.59 ± 86.63 mg/day. Volunteers were required to report any previous or current use of nutritional supplements, prescription and non-prescription medications. Participants were instructed to not change their nutritional supplement/medication intake over the course of the study and to report any changes to lab personnel.
Body composition was determined with the use of the Discovery QDR Dual-Energy X-ray Absorptiometry (DEXA) machine (Hologic, Inc., Bedford, MA). Participants were positioned in a supine position on the DEXA machine, in either workout shorts or hospital gown, and were asked to remain still during the entirety of the six minute scan. Percent body fat (%Fat), fat free mass (FFM; grams), and fat mass (FM; grams) were collected from the DEXA report. Height was obtained from the SECA 242 measuring instrument (242, SECA, Hanover, MD) and recorded in both centimeters and inches. The TANITA Body Composition Analyzer (Model TBF-310, TANITA, Arlington Heights, IL) was utilized to measure weight in both kilograms and pounds.
Resting energy expenditure
REE was measured using a TrueOne® 2400 metabolic measurement system (ParvoMedics, Sandy, UT). The metabolic cart was calibrated daily by trained laboratory assistants according to manufacturer guidelines. During testing, participants rested in a supine position with a blanket in a quiet, semi-dark room. A clear hood was placed over the participant’s head and upper torso area. REE and respiratory exchange ratio (RER) data were collected from the last 20 minutes of the 25 minute test. For each breath, mean oxygen uptake (VO2) and carbon dioxide output (VCO2) were measured and then averaged over 15 second intervals. Flow rate was monitored by lab assistants during the course of the test and maintained at a rate of 1–1.2 L/min of expired carbon dioxide. The test-retest correlations (r) of this metabolic cart range from 0.814-0.956 .
Mood state questionnaire
A 5-point Likert scale questionnaire was used to measure perceived alertness, focus, energy, fatigue, concentration, and hunger. The participant placed a check mark in the specific box that correlated with their perceived mood level for all six categories. The numbers ranged from one (not feeling that particular mood) to five (highest level of mood).
Electrocardiogram (ECG) leads were placed in standard clinical fashion to reveal 12 leads (I-III, V1-V6, aVR, aVL, aVF) throughout the testing session. Cardiac rhythm was monitored through a Quinton Eclipse Premier Electrocardiograph (Cardiac Science Corporation, Bothell, WA). Every five minutes, data were printed from the 12-lead ECG machine and RR interval, RP interval, QRS duration, and QT interval were recorded. If any abnormal readings/tracing were discovered, a note was added to the patient’s file. Heart rate, recorded as beats per minute and SBP and DBP, recorded as mmHg, were measured at baseline and hourly for four hours after consuming either treatment.
Participants were instructed to maintain a diet log for four days prior to the first testing session, testing day one, as well as days between testing sessions. Lab personnel instructed participants to report foods eaten at breakfast, lunch, and dinner, as well as snacks. They were also instructed to record the method of preparation for each food and the quantity eaten (servings, cups, tablespoons, etc.). Trained HPL assistants input the data from the diet logs into the Food Processor Nutrition and Fitness Software (ESHA Research, Salem, OR) computer program, which was used to determine caloric intake based on reported information from participants.
Our active supplement Dyma-Burn® Xtreme (Dymatize Enterprises, LLC, Dallas, TX) contains multiple ingredients combined to provide metabolic support including caffeine anhydrous, guarana, yerba mate green tea extract, L-carnitine L-tartrate (200 mg), pathothenic acid (17 mg), chromium picolinate (100 mcg) and proprietary blends containins , AssuriTea™ Green Tea Extract (Kemin Nutritionals, Iowa City, IA), Salvia sclarea, raspberry ketones and Capsicum Annum extract, plus l-tyrosine, salix alba (white willow), zingiber officinale (ginger), focus vesiculosus (bladderwrack), panax ginseng, and Bioperine® (black pepper extract). The total caffeine and catechin content of the supplement was 340 mg and 60 mg respectively.
Testing day timeline
Testing day timeline
REE (ending time)
Mood State Ques.
All data was analyzed in SPSS using a mixed-factorial ANOVA [treatment (DBX vs PLC) x time (HR1 vs HR2 vs HR3 vs HR4)]. When a significant interaction was found, a lower order ANOVA with Bonferroni post-hoc corrections was used. A Kruskal-Wallis one-way analysis of variance was also used for all survey data. Significance was set at p ≤ 0.05.
REE and RER
Hemodynamic and ECG
SBP, DBP, and HR Measurements Baseline to HR4
SBP mean ± SD (mmHg)
DBP mean ± SD (mmHg)
HR mean ± SD (bpm)
100.58 ± 12.12
105.58 ± 8.08
60.50 ± 7.20
62.08 ± 5.42
58.25 ± 5.07
56.58 ± 7.10
113.0 ± 9.04
107.33 ± 6.04
65.33 ± 9.03
62.75 ± 5.36
55.17 ± 7.09
54.00 ± 9.94
110.67 ± 13.36
105.58 ± 8.96
60.25 ± 13.06
61.08 ± 8.28
55.33 ± 6.41
55.58 ± 10.94
114.17 ± 19.00
103.08 ± 6.75
67.25 ± 20.01
57.58 ± 6.67
55.92 ± 6.11
56.08 ± 7.66
108.92 ± 7.44
107.17 ± 9.48
61.75 ± 5.33
63.25 ± 8.75
56.83 ± 6.64
56.25 ± 7.64
Subjective measures of mood state
The results from this study indicate that this particular thermogenic aid is capable of significantly increasing REE (+8%) for at least four hours post-ingestion in moderate-level habitual caffeine consumers. It is reasonable to contribute the increase in REE to the 340 mg proprietary blend of caffeine anhydrous, guarana, yerba mate, and green tea extract found in the commercially available DBX. Caffeine is a known stimulant and increases energy expenditure and weight loss. In combination with catechins, caffeine has been proven to decrease body fat percentage and waist circumference in overweight individuals . Increased fat utilization as a fuel source is another benefit often associated with caffeine ingestion and supplementation. A 2011 meta-analysis  concluded that while caffeine ingestion increases energy expenditure, it appears to be unable to increase fat oxidation unless paired with catechins. Fat oxidation was significantly increased when 375 mg of catechin was paired with 150 mg of caffeine , 540 mg catechin with 300 mg of caffeine , and when 662.5 mg of catechin was consumed with 270 mg of caffeine . The current study contradicts conclusions reported by Hursel and colleagues  as the Dyma-Burn® Xtreme supplement does contain a catechin-caffeine mixture but RER was not significantly changed over the four hour testing period (p > 0.05). This could possibly be explained by the lower level of catechin (50 mg) used in this particular product. More so, differences may be attributed to the use of both men and women with varying resting RER levels. The results of this investigation suggest that while DBX can promote a rapid and sustained increase in REE, the increase is not due to enhanced fat oxidation. Research from 2001  supports the RER data from the current investigation as Graham concludes that caffeine’s role as a glycogen sparing aid is not fully supported by research.
The active supplement promoted increases in perceptions of alertness, focus, and energy, and also decreased fatigue without impacting perceived anxiety levels. These findings suggest that this product might have a favorable impact on the perceived quality of daily activities including exercise. Here again, caffeine is the most studied of the active ingredients and believed to be the main contributing factor to the positive changes in alertness, focus, energy, and fatigue. In a study by Zwyghuizen-Doorenbos and colleagues , a dosage of 250 mg of caffeine increased alertness in healthy young men. Those consuming the caffeine also performed better than those who received the placebo. With this in mind, this supplement may be beneficial for persons looking to burn more calories throughout the day and increase exercise performance. Furthermore, the experimental design of this study was based on an acute response and it is unclear at this time what the effects might have on chronic exercise and training adaptations when the product is taken for several weeks.
Of interest is the potential real world application of this study considering all of the participants were habitual caffeine consumers with a moderate daily intake of caffeine (<200 mg/day) and were still responsive to the active supplement treatment. This regular intake of moderate amounts of caffeine may explain much of the lack of observed hemodynamic and ECG effects in this investigation. Tolerance to caffeine can develop within four days of consuming 150 mg/day  and this built-up tolerance can negate or reduce the side effects often seen when a non-caffeine user ingests a caffeine-containing beverage/supplement including increases in SBP, DBP, and changes in HR . In addition to a lack of negative physiological side effects, participants also did not report any negative mood states or other side-effects. When participants were given 280 mg of caffeine in the form of coffee, Smits and associates  observed an increase in BP and a decrease in HR, while there were no significant changes among the control group (decaffeinated coffee). These changes in HR and BP were assumed to be linked to the caffeine content of the regular coffee. Considering the supplement used in the present study contained 340 mg of total caffeine, habitual moderate caffeine usage seems to be the contributing factor to no significant changes in HR, BP, and ECG data, as well as the lack of reported side-effects.
In conclusion, when taken by moderate caffeine users that are physically active and healthy, the proprietary blend of this particular thermogenic supplement can increase REE and mood states related to alertness, focus, and energy without causing unsafe acute hemodynamic side-effects or increasing perceived anxiety levels. Future research should evaluate the chronic combined effects of DBX with exercise.
Resting energy expenditure
Respiratory exchange ratio
Systolic blood pressure
Diastolic blood pressure
Human performance Lab
Dual-Energy X-ray Absorptiometry
Percent body fat
Mean oxygen uptake
We would like to thank all of our participants for volunteering for the study as well as all of the research assistants in the HPL that assisted with data collection. We would also like to thank Dymatize Nutrition for sponsoring this study.
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