Going Vegan for the Gain: A Cross-Sectional Study of Vegan Diets in Bodybuilders during Different Preparation Phases

Abstract

Numerous athletes compete at a high level without consuming animal products; although a well-planned vegan diet might be appropriate for all stages of the life cycle, a few elements need to be addressed to build a balanced plant-based diet for an athlete, particularly in bodybuilding, in which muscle growth should be maximised, as athletes are judged on their aesthetics. In this observational study, nutritional intakes were compared in a cohort of natural omnivorous and vegan bodybuilders, during two different phases of preparation. To this end, 18 male and female bodybuilders (8 vegans and 10 omnivores) completed a food diary for 5 days during the bulking and cutting phases of their preparation. A mixed-model analysis was used to compare macro- and micronutrient intakes between the groups in the two phases. Both vegans and omnivores behaved similarly regarding energy, carbohydrate, and fat intakes, but vegans decreased their protein intake during the cutting phase. Our results suggest that vegan bodybuilders may find difficulties in reaching protein needs while undergoing a caloric deficit, and they might benefit from nutritional professionals’ assistance to bridge the gap between the assumed proteins and those needed to maintain muscle mass through better nutrition and supplementation planning.

Completely Plant-Based Diets That Meet Energy Requirements for Resistance Training Can Supply Enough Protein and Leucine to Maximize Hypertrophy and Strength in Male Bodybuilders: A Modeling Study

“…The protein recommendations used in this study align with recommendations for maximal muscular development in young, healthy adults [43]. They align with existing guidelines for athletes following plant-based diets [74] and corroborate evidence that athletes undertaking RET while following completely plant-based diets meet protein requirements for maximal gains in muscle mass and strength [40,75,76]. Our study calculated protein intakes of 1.8 g/kg/day, which exceeds the mean intake levels of 1.6 g/kg/day required to maximize RET-induced gains in muscle mass and strength in healthy adults [47].…”

“…However, the dietary assessment methods used in these studies, which consisted mainly of 3- to 7-day food diaries, are known to underestimate energy intake [ 73 ]. Moreover, a recent cross-sectional study by Amatori and colleagues (2023) reported a mean calorie intake of 2632 kcal/day among bodybuilders following completely plant-based diets [ 40 ]. This study estimated food intake using a digital food diary, which may also underestimate energy intake [ 73 ].…”

“…Our modeling was performed using an entirely male population with a median body mass of 84.5 kg. Subjects in the studies by Spendlove (2015) and Amatori (2023) included 84% and 61% male subjects, and mean body masses were 83.7 kg and 72.3 kg in these samples, respectively [ 8 , 40 ]. The former reported mean body mass for men and women separately, and the latter reported mean body mass for men and women combined, which may have contributed to the divergent body masses and energy intakes reported in these studies.…”

“…Caution, as well as careful planning and monitoring, has therefore been recommended to ensure that athletes following plant-based diets meet protein and amino acid needs [15,21,[33][34][35][36]. Studies of aerobically or anaerobically trained adults who engage in recreational or competitive sports do not indicate inadequate intakes of total protein, lysine, methionine, leucine, key micronutrients, or lower diet quality, in individuals who follow plant-based diets compared to omnivorous diets [37][38][39][40][41][42]. However, these reports included subjects who consumed large quantities of protein supplements, obfuscating an evaluation of whether completely plant-based diets as commonly consumed (without emphasis on protein supplements) would satisfy the elevated protein required for maximal RET-induced gains in muscle mass and strength [43].…”

“…Bodybuilders are unique among strength-sport athletes in that the pursuit of muscle hypertrophy is the primary aim of RET, rather than a secondary consequence of strength and power development training [ 44 ]. The nutritional adequacy of completely plant-based diets followed by bodybuilders has been described [ 40 ], but plant-based diets prescribed for muscular hypertrophy frequently rely on protein supplements to maximize the anabolic response to RET [ 38 , 42 ]. It remains uncertain whether individuals who engage in RET and follow completely plant-based diets composed largely of whole foods that meet hypercaloric intake levels recommended to maximize muscle mass accrual (i.e., “bulking”) need to carefully plan and monitor their diets to meet protein, leucine, and micronutrient requirements.…”