Download Full Text (187 KB)


Over the past decade, the health industry has increasingly targeted young females with supplements and nutri8on products. Energy drinks such as Reign Inferno market themselves as “thermogenic fuel,” promising to increase caloric expenditure at rest. The primary ingredient of products like Reign Inferno is caffeine. According to Belza et al. (2009), caffeine exerts a thermogenic response that can cause acute increases in res8ng metabolic rate (RMR). Res8ng metabolic rate (RMR) is measured via indirect calorimetry, which uses measures of oxygen consump8on (VNO2) and carbon dioxide produc8on (VNCO2) to approximate caloric expenditure from oxida8ve metabolism. At rest, VNO2 should be approximately 3.5 milliliters of oxygen per kilogram of bodyweight per minute (mL/kg/min), or 1 MET. RMR is used to calculate res8ng energy expenditure (REE), the body’s energy needs expressed in kilocalories per day (kcal//day). According to McArdle et al. (2015), primary determinants of res8ng metabolic rate are age, gender, stature, total body mass, and fat free mass. Respiratory quo8ent (RQ) is calculated by dividing VNCO2 by VNO2. RQ reflects fuel usage at a cellular level. An RQ of 1.0 indicates carbohydrate usage, while an RQ of 7.0 indicates fat is the sole fuel source. This is due to faZy acids’ larger hydroge cotet, which requires more oxyge for complete breakdown (McArdle et al., 2015). Given that caffeine has a therogenic effect, the first objec8ve of this experiment was to test the claim of the energy drink Reign Inferno by analyzing its effects on res8ng energy expenditure and other metabolic variables, including VNO2, minute ven8la8on (VNE), RQ, and heart rate (HR). According to Nehlig (2018), regular caffeine drinkers develop tolerance to peripheral ac8ons of caffeine, such as its effects on hormonal responses and heart rate. Therefore, a secondary objec8ve of this study was to determine compare metabolic responses in females who regularly consume more than 300 mg of caffeine (caffeine group) to those who consume less than 300 mg of caffeine daily (non-caffeine group). It is hypothesized that inges8on of a bodyweightcorrected amount of Reign Inferno energy drink will elevate res8ng metabolic rate in college-aged females, but will have a greater effect on those who consume less than 300 mg of caffeine daily.

Publication Date

Spring 2022


Boiling Springs, NC


Medicine and Health Sciences | Movement and Mind-Body Therapies | Rehabilitation and Therapy | Sports Sciences

Effects of caffeine consumpton on restng metabolic rate in college-aged females