Are there differences between strength-trained women following plant-based versus omnivorous diets? A pilot study examining anaerobic fitness, strength, body composition, and physical activity

Plant-based diets (PBD), consisting of both vegan and vegetarian diets, are being adopted more prevalently each year. While the health benefits and safety of the diet has been sufficiently proven, possible influences of PBDs on fitness and energy expenditure are less known. This cross-sectional study assessed differences in strength trained females for anaerobic capacity, strength and power, body composition, and energy intake/expenditure. Anaerobic power was assessed using a Wingate test and strength was assessed using isokinetic dynamometry in 12 individuals following a PBD and 8 following an omnivore (OMNI) diet. Body composition was assessed using the BodPod, food logs were recorded using ASA-24 and ActiHeart monitors tracked physical activity and energy expenditure. It was hypothesized that PBDs would have no significant negative effects on measures of strength, anaerobic power, body composition, or energy expenditure. It was also hypothesized that PBDs would show differences in dietary intake, specifically higher carbohydrate and lower fat intake. There were no significant differences in body composition between dietary groups (body fat %: 25.5 ± 5.8 % and 20.3 ± 6.6 % for PBD and OMNI respectively, p 0.05). While carbohydrate intake was higher for PBD (272 ± 58 g and 195 ± 59 g, p 0.05), overall energy intake did not significantly differ (1977 ± 456 kcals and 1780 ± 496 kcals for PBD and OMNI respectively, p 0.05). Although there was a trend for greater moderate physical activity in PBD, overall there were no differences in physical activity levels (1.97 ± 0.34 and 1.74 ± 0.12 for PBD and OMNI respectively, p 0.05). Peak (93.2 ± 23.4 ft·lbs-2 and 92.9 ± 20.7 ft·lbs-2 for PBD and OMNI respectively, p 0.05) and mean (79.2 ± 23.0 ft·lbs-2 and 82.6 ± 18 ft·lbs-2 for PBD and OMNI respectively, p 0.05) leg extension torque were not different between dietary groups. No differences were detected for peak (750 ± 168 W and 723 ± 171 W for PBD and OMNI respectively, p 0.05) and mean (433 ± 76 W and 472 ± 81 W for PBD and OMNI respectively, p 0.05) anaerobic power. Results show that PBDs have no negative influence on measures of body composition, energy intake/expenditure, and most importantly strength and anaerobic performance in strength- trained females.