Mouth rinsing with a sweet solution increases energy expenditure and decreases appetite during 60 min of self-regulated walking exercise

Carbohydrate mouth rinsing can improve endurance exercise performance and is most ergogenic when exercise is completed in the fasted state. This strategy may also be beneficial to increase exercise capacity and the energy deficit achieved during moderate-intensity exercise relevant to weight control when performed after an overnight fast. Eighteen healthy men (mean (SD); age, 23 (4) years; body mass index, 23.1 (2.4) kg·m⁻²) completed a familiarisation trial and 3 experimental trials. After an overnight fast, participants performed 60 min of treadmill walking at a speed that equated to a rating of perceived exertion of 13 (“fairly hard”). Participants manually adjusted the treadmill speed to maintain this exertion. Mouth rinses for the experimental trials contained either a 6.4% maltodextrin solution with sweetener (CHO), a taste-matched placebo (PLA), or water (WAT). Appetite ratings were collected using visual analogue scales and exercise energy expenditure and substrate oxidation were calculated from online gas analysis. Increased walking distance during CHO and PLA induced greater energy expenditure compared with WAT (mean difference (90% confidence interval); 79 (60) kJ, P = 0.035, d = 0.24; and 90 (63) kJ, P = 0.024, d = 0.27, respectively). Appetite area under the curve was lower in CHO and PLA than WAT (8 (6) mm, P = 0.042, d = 0.43; and 6 (8) mm, P = 0.201, d = 0.32, respectively). Carbohydrate oxidation was higher in CHO than PLA and WAT (7.3 (6.7) g, P = 0.078, d = 0.47; and 10.1 (6.5) g, P = 0.015, d = 0.81, respectively). This study provides novel evidence that mouth rinsing with a sweetened solution may promote a greater energy deficit during moderate-exertion walking exercise by increasing energy expenditure and decreasing appetite. A placebo effect may have contributed to these benefits.