The purpose of the current study was to explore the general nutrition practices in competitive powerlifters. To our knowledge, this is the first study to characterise the general nutrition practices of powerlifters across competitive calibre, and sex, weight and, age class. There are several key findings: (1) Powerlifters use IIFYM/flexible dieting year-round, and during the competition preparation and off-season phases for performance and diet enjoyment; (2) nutrition strategies differ between competitive phases and there are various approaches to the competition phase; (3) female powerlifters are more conscious of EI than male counterparts; and (4) powerlifters focus on adequate EI on hard training days, but refrain from tailoring EI to the lower training workload on rest/easier training days.

Nutrition practices and the competitive cycle

IIFYM is popular in various fitness communities and the findings of the present study indicate that this approach is also popular with powerlifters as a long-term approach to the diet (Fig. 2), and within the competition preparation (Fig. 3) and off-season (Fig. 5) phases. IIFYM is characterised as a meal plan constructed to reach specific daily targets in grams of protein, CHO, and fats without a restriction on food source [14, 15]. Given this, IIFYM allows for more dietary inclusion and variety, and supports periods of weight gain, loss, or maintenance [14]. In the current study, IIFYM was paired with flexible dieting, the latter of which can be considered a distinct concept specific to weight loss. Cognitive restraint during phases of weight loss, to create a caloric deficit, is required on behalf of the dieter, and the approach to cognitive restraint has been characterised as an individual exerting more ‘flexible’ or more ‘rigid’ control, as scored on the three-factor eating questionnaire [20]. A rigid approach to dieting describes an all or nothing approach to eating behaviours and dieting, where ‘off-limit’ foods are avoided or eliminated and ‘diet’ foods are emphasised, narrowing the variability of foods consumed [21]. Flexible control represents a more moderate, balanced approach to dieting for weight loss that includes eating behaviours such as taking smaller servings of food than desired to regulate weight and including a variety of foods in limited quantities [16]. Thus, flexible dieting for weight loss can be considered more consistent with, but conceptually different to, the IIFYM approach to organising the diet.

IIFYM emphasises reaching daily targets for macronutrients but does not necessarily consider micronutrient intakes and it is presently unknown whether powerlifters reach the recommended dietary allowance (RDA) for micronutrients with an IIFYM approach. Micronutrient intakes below the RDA have been reported in bodybuilders [22] but micronutrient intakes have not been quantified in powerlifters. Recently, in a cohort of bodybuilders, Ismaeel et al., [14] reported intakes of vitamins A, D, and E; potassium; and fibre below the RDA, with similar prevalence between males following a macronutrient-based diet and those following a more rigid, ‘strict’ diet. Additionally, while there was a low sample size of female bodybuilders, those following an IIFYM approach reported higher, but still inadequate, micronutrient values compared to strict dieting females, and all females reported iron intakes below the RDA [14]. The prevalence of iron deficiency is 15–35% in athletic, female populations [23]. Female athletes consuming lower EIs, practicing vegan or vegetarian diets, and participating in endurance sports are notable factors in the prevalence of iron deficiency [24]; however, it is presently unknown to what degree female powerlifting athletes are affected. Future research is necessary to quantify the micronutrient intakes of powerlifters across specific competitive phases and identify any shortcomings in micronutrient intake in comparison to RDA.

Nutrition practices differ for specific competitive phases

IIFYM/flexible dieting was most often followed during the competition preparation (Fig. 3) and off-season phases (Fig. 5). However, the findings for competition phase (day of competition and the 48 h prior) diet (Fig. 4) indicate a variety of diet strategies, as the frequency of the five most popular diet selections were in the range of 20–40%. In addition, the diet strategies reported for the competition phase contrasted each other, as high and low-calorie diets were reported, and so were high and low (with high protein) CHO diets (Fig. 4). Females more often reported than males implementing dietary approaches which were almost exclusively (90%) implemented to lose weight/body composition goals (Fig. 4), such as restricted/low calorie or high protein with low CHO diets. There were also competitive calibre sub-group differences, as powerlifters with 80 + IPF points more often than 79- IPF points reported IIFYM/flexible dieting and/or a restricted energy diet during the competition period (Fig. 4). The results suggest that powerlifters following a high CHO and/or energy diet prioritise training performance in the days before competition, those following a restricted energy or high protein, low CHO diet prioritise weight loss/body composition, and those following IIFYM/flexible dieting perceive that this diet allows for them to maintain training performance and meet their weight loss/body composition goals. It should be noted that calorie restriction (possibly paired with fasting) and body water storage manipulation are common strategies used by powerlifters for inducing acute weight loss prior to the weigh-in that occurs on the day of powerlifting competition (2 h before) [9]; thus, the findings for the competition phase in the present study likely capture some of these acute weight loss strategies.

Energy intake practices differ by sex

Several of the findings from the present study indicate that females more often than males follow diets that restrict energy or do not allow for higher energy intakes. For example, long-term use of very high energy diets was reported less among female powerlifters (Fig. 2) and more often reported following a restricted energy diet during competition preparation (Fig. 3) and competition (Fig. 4) than their male counterparts. The total energy expenditure associated with powerlifting training is likely lower compared to other forms of exercise (e.g., endurance); hence, dietary restriction is likely to feature as the primary strategy for achieving a desired body weight or composition [25]. While dietary restriction is common in weight class restricted sports, it is also frequently accompanied by disordered eating in such athletes [26]. More so, disordered eating behaviour is prevalent in female athletes competing in sports emphasising leanness and weight restricted sports [27], and female athletes more often report symptoms of disordered eating than males [28]. Given the weight-class categorisation of powerlifting and that body leanness and weight are key competition performance variables, powerlifting athletes may be at more of a risk of developing disordered eating behaviours.

Despite the likelihood that powerlifters are susceptible to disordered eating, there is minimal scientific inquiry investigating disordered eating in powerlifters (and other strength sports). In a qualitative analysis of disordered eating in competitive female powerlifters (n = 17), weight cutting behaviours were common and associated with disordered eating [29]. The weight class element of powerlifting may present a paradox for some female powerlifters, in which the desire to increase muscle mass (to aid performance) must be balanced against societal ideals for the female body (e.g., to decrease body weight and/or weight class) [29]. Indeed, in previous research, female athletes frequently diet to improve appearance, which was contrasted by males, who most often reported dieting for performance outcomes [30]. Future research is necessary to further elucidate the prevalence of disordered eating behaviours and eating disorders amongst powerlifters (including males [31]).

One possible consequence of disordered eating behaviours is low energy availability (defined as: EI – energy expenditure/FFM), which can occur without disordered eating behaviours (especially in high energy expenditure athletes) [32], but is often underpinned by disordered eating behaviours in female [28, 33] and male athletes [28, 34]. Impaired energy availability could potentially lead to adverse outcomes (e.g., reproductive and skeletal health) such as those included in the Female Athlete Triad [35] and Relative Energy Deficiency in Sports [36], that could foremost negatively affect general health, and training performance, recovery, and adaptation. A prolonged EI below an approximate threshold of < 30 kcal/kg of FFM/day is considered detrimental to physiological function in female athletes [37], although it is less clear whether this threshold is applicable to male athletes [38]. Importantly, a powerlifting athlete may be weight stable and at energy balance but be in a state of low energy availability and experiencing the associated symptoms due to suppressed physiological function [39]. Conversely, adequate EI to support physiological function may need to reach or exceed 45 kcal/kg of FFM/day in some cases [39]. Notably, while these recommendations provide a useful target for EI, a reliable estimation of dietary intake and body composition is needed to accurately implement them and assistance from a sport nutrition or dietetic and/or exercise physiology professional is recommended [35]. Dietary intake of powerlifting athletes could be assessed using dietary logs and food frequency questionnaires, but can be subject to error from underreporting, modified intake caused by and during the measurement period, and inaccurate portion size estimation [40]. In athletic populations, body composition can be estimated with specialised technologies (e.g., dual x-ray absorptiometry, bioelectrical impedance) and field-based measures such as skinfolds [41]. Aided with this information, current recommendations are for physically active women to consume at least 45 kcal/kg of FFM per day to ensure adequate energy availability for physiological function, and between 30 and 45 kcal/kg of FFM per day during periods of intentional weight loss [25, 35].

The source of information informing nutrition practices should also be considered in the context of disordered eating behaviours. In the present study, the coach was the most often cited in-person source of information and females more often than males reported their coach as the source of information to inform hard training day nutrition practices. In previous research, coaches were identified as a prevalent source of information ahead of nutrition practitioners [42]. The coaching environment can increase or reduce risk of eating disorder [43]; thus, it may be beneficial for nutrition practitioners to educate powerlifting coaches on the importance of energy availability, the symptoms of low energy availability, and potential low energy availability management strategies (including the use of a multi-disciplinary team e.g., sport nutrition and mental health practitioners).

Harder versus easier training day energy periodisation

The energy cost associated with resistance training increases with greater training volumes and exercises that recruit more muscle mass [44]. Thus, athletes may modify their daily EI in accordance with the training demands on the day. For example, decreasing EI on lower volume training days or rest days may better manage EI during the weight cut before competition. Conversely, such a strategy may allow for an increased EI on harder, higher volume training days where the energetic demands of training are higher. Indeed, these strategies were observable in the present population as most powerlifters (71.8%, n = 219) reported intentionally and purposely eating more food/calories on all harder training days with higher training load the most often cited reason for this practice (87.6%, n = 192), compared to normal dietary intake. In contrast, most powerlifters reported not lowering their food/calorie intake on rest/easier training days compared to normal dietary intake (61%, n = 186) (Fig. 7). Strategies to estimate EI typically include dietary logs, questionnaires, and using smart phone dietary tracking applications [45]. While such estimates may contain notable error [40], they are likely preferred to making no such estimation. Another simple, less precise approach with potential utility is estimating energy expenditure from resistance training with the Metabolic Equivalent of Task method and the associated 2011 Compendium of Physical Activities [46]. When doing so, the energy expenditure of an activity in kilocalories = metabolic equivalent of the task x body weight in kilograms x duration of the activity in hours. Taken together, athletes and practitioners have several energy expenditure estimation tools at their disposal that, while limited, allow powerlifting athletes to tailor their EI to the energetic demands of their training.

Limitations

There are several limitations to the current study. Firstly, our analysis relies on self-reported nutrition practices and the questionnaire described diet practices without defining concepts (e.g., IIFYM) or specific amounts required (e.g., what constitutes ‘high’ or ‘low’ CHO). It is unknown how much of a difference there is between reported dietary trends (e.g., high or low intakes) and actual intake in the current study, since previous work in endurance athletes has observed some discrepancies (up to ~ 35%) [47, 48]. These discrepancies may be explained by participant bias or because responses may reflect what the participants strive or perceive to achieve, rather than actual intake. In the present survey, participants were required to be at least 18 years old to be eligible for inclusion, which excluded younger sub-junior powerlifters (14–17 years old). While sub-junior (at least 18 years old) and junior (19–23 years old) powerlifters were pooled in the analysis, the findings may not generalise to sub-junior powerlifting competitors less than 18 years old. In addition, only 21% of participants (n = 65) were female, which may limit the generalisability of the results. Lastly, the large, global sample size in the current study enabled an exploration of nutrition practices across competitive calibre, and weight, sex, and age classes. However, since most participants (84%) in this study were from North America and Europe, the findings may not be representative of powerlifters in other regions. Various factors, including cultural and socioeconomic influences, among many others, could contribute to differences in food choice [49].