Combining an exercise and nutritional intervention is arguably the optimal method of creating energy imbalance for weight loss. This study sought to determine if 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 BMI: 22.7 ± 2.6 kg∙m-2) completed a resting control trial (CON), a placebo exercise trial (EX), and a caffeine exercise trial (EX+CAF, 2x 3 mg∙kg-1 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 VO2max 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 to EX (+250 kJ; +10.4 g) and CON (+3126 kJ; +29.7 g) (P < 0.05). A trend for reduced energy and fat intake compared to 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 energy deficit and the implications of this protocol for weight loss or maintenance over longer time periods in overweight/obese populations require further investigation.
- fat oxidation
- exercise enjoyment
- Copyright © 2014, Journal of Applied Physiology