An Evaluation of the Nutritional Practices and Energy Requirements of Elite Female Soccer Players: A Mixed Methods Investigation

McHaffie, S (2026) An Evaluation of the Nutritional Practices and Energy Requirements of Elite Female Soccer Players: A Mixed Methods Investigation. Doctoral thesis, Liverpool John Moores University.

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Abstract

In recognition of the increasing growth and professionalism of the women’s game (Fédération Internationale de Football Association, 2017, 2019; Petty and Pope 2019), there have been multiple calls for a strategic and multidisciplinary research agenda that seeks to improve the health and performance of the female soccer player (Datson et al. 2017; Nassis et al. 2021). Indeed, in a recent audit of research, it was demonstrated that the existing research base is not comparable to the men’s game (Okholm Kryger et al. 2021). In terms of potential research priorities, this audit identified that nutrition-related research is less studied when compared with other sub-disciplines of sport and exercise science (Okholm Kryger et al. 2021). Furthermore, the nutritional guidelines that are currently directed to female athletes are based on research primarily conducted on males (Moore et al. 2021). This lack of female specific research is of concern given that female athletes are susceptible to chronic low energy availability (Heikura et al. 2021), the result of which can manifest as symptoms associated with the female athlete triad or relative energy deficiency in sport models (Nattiv and Lynch 1994; Mountjoy et al. 2023). Therefore, the aim of this thesis was to determine energy requirements and current nutritional practices of elite female soccer players, using a mixed methods approach.

Based on previous observations suggesting the existence of under-fuelling within this population, the aim of Study One was to qualitatively explore player and stakeholder perceptions of nutrition practices in support of female soccer players’ development and performance. Semi-structured interviews (36 ± 18 mins in length) were conducted with 47 participants, including players (n = 12), parents (n = 9), coaches (n = 9), sport scientists (n = 7), nutritionists (n = 5) and medical staff (n = 5). Via thematic analysis, data provided an insight into the nutrition culture within elite women’s soccer. Data demonstrate that considerable confusion and misconceptions exist amongst players and stakeholders regarding the theoretical underpinning and practical application of meeting energy requirements. As such, it is perceived that players ‘under-fuel’, which is likely caused by misunderstandings about the impact of carbohydrate intake on body composition, a fear of weight gain and the associated impact upon body image. The ‘carbohydrate fear’ that is experienced by players is exacerbated by external pressures arising from social media, key stakeholders (e.g., coaches) and the skinfold culture surrounding measurement of body composition. Such cultural issues are amplified by the lack of full-time professionally accredited nutritionists overseeing the provision of nutrition support. Indeed, the infrastructure supporting the women’s game (e.g. staffing resource, on-site food provision, player education programmes, etc.) was considered incomparable to the men’s game. When taken together, our data provide a platform for which to develop organisational, stakeholder and player centred education and behaviour change interventions that strive to promote a positive performance nutrition culture within the women’s game.

Given the perceived practice of under-fuelling and the associated implication for menstrual cycle irregularities, the aim of Study Two was to qualitatively explore player and stakeholder perceptions of menstrual health support within elite female soccer. Using the same methodology and participant group as Study One, data demonstrate that elite female soccer players experience a range of physical and psychological symptoms primarily at the onset of and during menses (as also perceived by stakeholders), with most participants perceiving these symptoms to impact performance. Nonetheless, menstrual health support is perceived as minimal and although players have their menstrual status tracked, they report little understanding as to why or how this information is used. This confusion was also present among stakeholders, often as a result of uncertainty about the evidence supporting the need for menstrual health support. The perceived lack of support may also be reflective of a culture where conversations about the menstrual cycle are not normalised. Overall, this may result in failure to identify and treat menstrual irregularities despite non-coaching staff members perceiving them to be common amongst players. These data support the need for individualised support based on the lived experiences of individual players and support staff. Furthermore, our research identifies the need for organisational, stakeholder and player centred education programmes (led by experts in female athlete health) that create an environment where players receive personalised menstrual health support.

Study One qualitatively explored a culture of under-fuelling within the women’s game (as comprising both adult and adolescent players), the consequence of which may have acute performance and chronic health implications. However, the dietary practices of “adolescent” players, a population who may be particularly at risk of negative implications of under-fuelling, are yet to be explored. Accordingly, within Study Three we aimed to quantify energy and carbohydrate intake, physical loading and estimate energy availability in international adolescent female soccer players (n = 23; age, 17.9 ± 0.5 years) during a 10-day training and game schedule comprising two match days on days six (MDa) and nine (MDb). The players self-reported their energy intake via the remote food photography method, whilst the physical loading and associated exercise energy expenditure were assessed via global positioning system technology. The relative carbohydrate intake was significantly greater (all p < 0.05) on the day before the first match (MD-1a) (4.1 ± 0.8 g·kg−1), on the day before the second match (MD-1b) (4.3 ± 1.1 g·kg−1), MDa (4.8 ± 1.2 g·kg−1) and MDb (4.8 ± 1.4 g·kg−1) in comparison to most other days to most other days (<4 g·kg-1). The mean daily measured energy availability over the 10-day period was 34 ± 12 kcal·kg FFM-1·day-1 (with six players, i.e., 34%, presenting low energy availability), though, when adjusting the energy intake for potential under-reporting, these values changed substantially (44 ± 14 kcal·kg FFM-1·day-1, only one player was classed as presenting low energy availability). Such data suggest that the prevalence of low energy availability amongst female team sport athletes may be over-estimated. Nonetheless, players may still be under-fuelling for the work required in relation to daily CHO recommendations (i.e., >6 g·kg-1) for intensive training and game schedules. These data provide further evidence for the requirement to create and deliver targeted player and stakeholder education and behaviour change interventions (especially for younger athletes) that aim to promote increased daily carbohydrate intake in female soccer players.

It is acknowledged within Study Three that low energy availability may be overestimated in previous research, given the inaccuracies of directly measuring energy intake. Therefore, a gold standard approach to exploring the prevalence of low energy availability and accuracy of energy availability assessment within this population is required. Accordingly, Study Four aimed to quantify total daily energy expenditure (via the doubly-labelled water method), energy intake and energy availability. Adolescent female soccer players (n = 45; 16 ± 1 years) completed a 9–10 day ‘training camp’ representing their national team. Absolute and relative total daily energy expenditure was 2683 ± 324 and 60 ± 7 kcal.kg-1 FFM, respectively. Mean daily energy intake was lower (P < 0.01) when players self-reported using the remote food photography method (2047 ± 383 kcal.day-1) over a 3-day period versus doubly labelled water derived energy intake, accounting for body mass changes (2545 ± 518 kcal.day-1) over 7–8 days, representing a mean daily Δ of 499 ± 526 kcalday-1 and 22% error when using the remote food photography method. Estimated energy availability was different (P < 0.01) between methods (doubly labelled water: 48 ± 14 kcal.kg-1 FFM, range: 22–82; remote food photography method: 37 ± 8 kcal.kg-1 FFM, range: 22–54), such that prevalence of low energy availability (<30 kcal.kg-1 FFM) was lower in doubly labelled water compared with remote food photography method (5% vs. 15%, respectively). Data demonstrate the potential to significantly underestimate energy intake when using self-report methods. This approach can therefore cause a misrepresentation and an over-prevalence of LEA, which is the underlying aetiology of ‘relative energy deficiency in sport’.

In summary, this thesis used a mixed methods approach to assess nutritional practices and energy requirements of elite female soccer players. To meet daily energy requirements, data demonstrate that total daily carbohydrate intake should at least be equivalent to 5 g.kg BM.day-1. However, the nutrition culture within the women’s game may not always be conducive to optimal fuelling practices, owing to challenges associated with social opportunity (e.g. social media, comments, etc.) and reflective motivation, all of which are aligned around player and stakeholder perceptions of optimal body composition. Despite previously observation of low energy availability within this population, the data also demonstrate that prevalence of low energy availability is likely over-estimated primarily because of inaccuracies associated with dietary assessment methods. When taken together, this thesis provides a platform for which to formulate targeted education and behaviour change strategies for players, stakeholders and practitioners alike.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	soccer; LEA; Energy Expenditure; Energy Intake
Subjects:	T Technology > TX Home economics > TX341 Nutrition. Foods and food supply G Geography. Anthropology. Recreation > GV Recreation Leisure > GV561 Sports
Divisions:	Sport and Exercise Sciences
Date of acceptance:	18 December 2025
Date of first compliant Open Access:	29 January 2026
Date Deposited:	29 Jan 2026 13:37
Last Modified:	29 Jan 2026 13:38
DOI or ID number:	10.24377/LJMU.t.00027943
Supervisors:	Morton, J, Langan-Evans, C, Areta, J and Strauss, J
URI:	https://researchonline.ljmu.ac.uk/id/eprint/27943

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