Are You Depleting Your Body's Energy Reserves?
If you're an active woman, you may be susceptible to experiencing low energy availability and its associated health risks. Here's what you should be aware of:
When researchers examine the dietary intake of female athletes, a concerning number of them are not consuming enough nutrients to support both their athletic performance and overall well-being.
Here are a few noteworthy instances from recent research, demonstrating the prevalence of low energy availability (LEA) and its adverse health effects among female athletes in various sports:
Nearly 80 percent of elite female cross-country runners in one study were found to be at risk of LEA.
In another study, 88 percent of professional female soccer players were identified as having LEA.
A study involving ballet dancers revealed that 96 percent of them were at risk of LEA.
Shockingly, all synchronized swimmers examined in a study had low energy availability.
In a more comprehensive study conducted in 2022, involving over 200 female endurance athletes and published in Frontiers in Sport and Active Living, it was reported that 65 percent were at risk of LEA, 23 percent were at risk of developing exercise addiction, and 21 percent exhibited disordered eating behavior.
Low energy availability is a concern that I encounter regularly, and if not addressed promptly, it can potentially lead to irreversible health issues such as dangerously low bone mineral density.
What is LEA?
From a technical standpoint, low energy availability (LEA) is defined as having insufficient energy remaining to support your regular bodily functions after deducting the energy expended during exercise from your total dietary energy intake.
In simpler terms, this means that you're not consuming enough calories to adequately support both your training regimen and your fundamental biological requirements. This is what makes LEA particularly concerning. You might still be able to engage in activities like running, swimming, cycling, weightlifting, and other workouts (at least for a while), but your body lacks the necessary calories and nutrients to sustain optimal operation of your organ systems.
When this occurs, your body enters a state of LEA, which my former Ph.D. student and current doctorate holder with expertise in LEA, Dr. Katie Schofield, compares to how your smartphone goes into low battery mode. In this mode, the device can still function, but the screen dims, and some applications begin shutting down to conserve energy. However, in the case of your body, these "applications" are your organ systems, including your reproductive and endocrine systems!
What Are the Consequences of Low Energy Availability (LEA)?
Prolonged low energy availability (LEA) can have severe implications for your health. One of the most significant consequences is its impact on your reproductive system. Many female athletes mistakenly believe that losing their menstrual periods during training is normal, but it is far from it. Research indicates that when women experience LEA, it disrupts the production of luteinizing hormone, which is vital for ovulation and regulating the menstrual cycle.
Disrupting your hormones with LEA can lead to serious and potentially enduring adverse effects on your skeletal system. Inadequate energy intake impairs the functioning of osteoblasts (cells responsible for building bone) and osteoclasts (cells responsible for breaking down and resorbing bone), resulting in a breakdown of bone exceeding its formation. The end result includes bone stress injuries, stress fractures, and an elevated risk of osteoporosis in the long run.
LEA can also give rise to a range of other health issues, including irritability, bouts of depression, cognitive fog, compromised immunity, reduced libido, gastrointestinal problems like constipation and diarrhea, and nutritional deficiencies like anemia.
Furthermore, it can hinder muscle growth. Recent research involving 30 physically active, menstruating females revealed that when they trained (both endurance and resistance exercises) with LEA for ten days, they experienced impaired myofibrillar and sarcoplasmic muscle protein synthesis, compared to when they trained with optimal energy availability, defined by researchers as 50 kcal per fat-free mass (FFM) per day. This also resulted in reductions in lean mass, urinary nitrogen balance, free androgen index, thyroid hormone levels, and resting metabolic rate. Researchers concluded that LEA could negatively affect skeletal muscle adaptations.
It's evident that LEA can also compromise your athletic performance. However, depending on your sport, you may not immediately notice decrements, and in some cases, you might even see improvements for a period of time. This is because LEA is primarily about not having enough energy reserves after training, rather than the training itself. Consequently, chronic LEA can adversely affect muscular adaptations and muscle protein synthesis, but it may go undetected for extended periods before performance plateaus and declines. Moreover, it's possible to inflict damage, such as bone loss, before reaching that critical point.
Recognizing Low Energy Availability (LEA):
Identifying LEA early on is crucial to prevent it from evolving into a severe health issue. Here are some clear indicators that you may be experiencing low energy availability:
Irregular or absent menstrual cycles
Persistent fatigue
Mood disturbances, such as irritability and depression
Frequent illness
Frequent injuries, particularly stress reactions and fractures
Decreased libido
Increased gastrointestinal problems
Impaired or reduced training adaptations
How to Overcome and Prevent Low Energy Availability (LEA):
Addressing LEA can be a challenging endeavor, as there are various reasons why female athletes might find themselves in this state. Some reasons are deliberate, such as following restrictive diets and reducing carbohydrate intake. Others are unintentional – women may believe they are consuming enough calories, but they are not. Most commonly, insufficient nutrition is observed around training sessions; delaying food intake after exercise keeps the body in a catabolic (breakdown) state, signaling to the brain that there isn't enough energy to support adaptation and overall health. If you have a history of disordered eating, restrictive eating patterns, or an outright eating disorder, seeking professional guidance should be your initial step.
So, how can you determine if you're inadvertently entering LEA territory? If you know your body composition, you can start by using the equation to calculate energy availability (EA). EA is calculated as your dietary energy intake (in kcal) minus your exercise energy expenditure (in kcal), divided by your fat-free mass (FFM) in kilograms (kg). Ideally, you want the resulting EA value to be over 45 calories per kilogram of FFM, and aiming for 50 calories per kilogram of FFM is advisable if you engage in regular training. Anything below 30 calories per kilogram is defined as LEA, and health risks can start manifesting in as little as five days at this level.
As an example, consider an active female weighing 64kg (140lb) with 19% body fat, burning approximately 400 calories during her daily gym session. To surpass the 45-calorie/kg FFM benchmark, she would need to consume about 2,800 calories per day. If this seems high, it's essential to recognize that conventional diet culture often promotes a harmful message of women limiting themselves to 1,200 calories per day – a message that has no relevance to active or athletic women.
Realistically, many women may struggle to consistently reach these EA targets, even with good intentions. Therefore, it's crucial to be mindful of refueling within 30-45 minutes after training to prevent the brain from perceiving low energy intake. Avoiding extremely low-carb or ketogenic diets is also advisable, as research suggests that adequate carbohydrate consumption may help prevent LEA, even when EA is not at an optimal level.
While I generally do not advocate strict calorie counting or macro tracking, it can be beneficial to keep a record for three to five days to compare actual energy intake to your perceived intake. You might be surprised by the difference.
The next step involves increasing your calorie intake around your training sessions and throughout the day. Observe how you feel and perform when you meet these energy requirements. Many athletes experience a significant improvement in their performance once they meet their energy needs.
