The MOST IMPORTANT Nutritional Strategy for Female Athletes
Late last year Ackerman and colleagues released an important paper regarding nutritional considerations for the health and performance of female athletes (Holtzman & Ackerman, 2021). The paper highlighted that “nutrition is an important aspect of an athletes preparation to achieve optimal health and performance” with the development of a hierarchy of nutritional needs and considerations for female athletes (figure 1). In the same manner as Maslow’s hierarchy of needs, this nutritional pyramid denotes that a female athlete should meet baseline needs before moving up to subsequent levels. Consistent with the majority of research surrounding female athlete health and performance, energy availability (EA) was considered the number one priority when it comes to nutritional considerations (Holtzman & Ackerman, 2021).
Energy availability has been operationally defined as energy intake (EI) minus exercise energy expenditure (EEE) relative to fat free mass (FFM) (Loucks & Thuma, 2003). It is the energy available for normal physiological functioning such as resting metabolic rate, muscle recovery and cognition after exercise energy expenditure has been accounted for (Mountjoy et al., 2014). In order to optimise health & wellbeing, data suggests that female athletes should aim for an EA of ~45kcal/kg/FFM (Loucks & Thuma, 2003). This supports the functioning of physiological systems, training adaptations, and ultimately optimal athletic performance. For example a 60 kg female footballer training for 90 minutes in a single day would expend approximately 700 calories. Assuming this athlete has a FFM of 50 kg, in order to calculate the amount of calories required to achieve an energy availability of 45kcal/kg/FFM we would need to multiply 45 by 50 and add this to the 700 calories burned during training. This would equate to approximately 2950 calories for that day – which requires consumption of a significant amount of food!
Unfortunately, there is significant evidence that female athletes fail to account for changes in exercise energy expenditure through their energy intake and may experience appetite suppression (Dobrowolski & Wlodarek, 2020; Magee et al., 2020; Moss et al., 2021). When female athletes have inadequate EA they can enter a state of low energy availability (LEA) defined as, “an inadequacy of energy to support the range of body functions involved in optimal health and performance” (Mountjoy et al., 2014). This is the underlying cause of a syndrome defined in 2014 by the International Olympic Committee (IOC) as Relative Energy Deficiency in Sport (RED-S).
Low energy availability impacts the physiological functioning of numerous bodily systems and an athlete in a state of chronic LEA puts themselves at risk of serious acute and long term health consequences (Mountjoy et al., 2014). One of the biggest impacts of LEA, is it’s disruption to endocrine function and subsequently the process of menstruation in females (Mountjoy et al., 2014). These initial changes to menstrual cycle function present as anovulatory or irregular menstrual cycles (oligomenorrhea) and in severe cases the absence of menstruation (amenorrhea). The proposed threshold for a state of LEA in females has been suggested to be less than 30 kcal/kg FFM (Loucks & Thuma, 2003).
Research has subsequently demonstrated how menstrual cycle disruptions can be accompanied by an array of other health consequences “including, but not limited to, metabolic rate, menstrual function, bone health, immunity, protein synthesis and cardiovascular health”, as well as a profound effect on athletic performance (Mountjoy et al., 2014). However, the impact of the intensity of LEA (kcal/kg/FFM values), the duration or how long an athlete has been below the threshold of <30 kcal/kg FFM and frequency of LEA (how many times have they been in a state of LEA in the last 12 months) relative to the extent of disruption of the females physiological functioning, or degree of adverse health symptoms is still an active area of investigation and may vary among individuals (Burke et al., 2018).
Research consistently shows that during periods of intense training, female athletes fail to match their energy intake with high or increasing exercise energy expenditure and therefore, they are not getting adequate EA (Dobrowolski & Wlodarek, 2020; Moss et al., 2021). Inadequate EA may be an unintentional by-product of athletes experiencing post exercise appetite suppression (Howe et al., 2016) or increased training load, as well as having insufficient nutritional knowledge or support to aid them in increasing their EI (Costill et al., 1988). In contrast, reduced EA can also be a purposeful decision in which a female athlete chooses to restrict caloric intake in order to either enhance sport performance or meet aesthetic demands of the sport, or perceived societal pressure (Mountjoy et al., 2018). If you or one of your athletes is experiencing the former, then there are several practical strategies that can be applied to help improve EA and thereby the health and wellbeing of the female athlete.
These strategies can be broken down into three main areas; energy intake, volume and intensity of exercise and psychological stress. Ideally you want to address energy intake and psychological strategies first as these will not jeopardise an athletes training schedule. However, in severe cases of LEA, the type, intensity and volume of training will need to be adjusted.
Energy Intake Strategies
1. Consume 3 large meals and 2-3 smaller snacks per day
2. Increase total carbohydrate intake to ~60-70% of the diet
3. Eat a protein + carbohydrate rich snack prior to and immediately after training (especially if they are long or intense)
4. On high intensity or bigger training days compensate by adding in another snack and/or meal.
5. Struggling with feeling too full
a. increase dietary fats or energy dense foods
b. reduce fibre