Are You Draining Your Body’s Battery Power? [Revised]

fueling low energy availability nutrition undernourished Aug 03, 2023
LEA with Dr Stacy Sims

If you’re an active female, chances are you’re at risk for low energy availability and the health consequences it brings. Here’s what you need to know. 

When researchers screen the nutritional intake of female athletes, a staggering percentage are not eating enough to support their performance and their health.

Here are just a few examples of how many female athletes in various sports were at risk for low energy availability (LEA) and the detrimental health consequences it brings, according to recent research:

  •  Nearly 80 percent of elite female cross-country runners show risk for LEA in this study.
  •  88 percent of professional female soccer players had LEA in this study
  •  96 percent of ballet dancers had LEA in this study.
  •  100 percent of synchronized swimmers had low energy availability in this study!

More broadly speaking, a 2022 study of more than 200 female endurance athletes published in Frontiers in Sport and Active Living reported that 65 percent were at risk of LEA, 23 percent were at risk of exercise addiction, and 21 percent had disordered eating behavior. 

LEA is a problem I see every day, and if it isn’t caught in time, it can sometimes lead to irreversible damage to your health, such as dangerously low bone mineral density.

What is LEA?

Technically speaking, low energy availability, or LEA, is defined as having limited energy available to support your normal body functions once your energy expended through exercise is subtracted from your total dietary energy intake. 

Plainly speaking, that means you’re not eating enough to support both your training and your basic biological needs. This is what makes LEA particularly insidious. You may be able to run, swim, bike, lift and otherwise complete your workouts (at least for a while), but your body doesn’t have enough calories and nutrition left over to keep your organ systems operating at optimal levels. 

When this happens, your body enters a state of LEA, which my former Ph.D. student and now doctorate specializing in LEA, Dr. Katie Schofield, likens to how your phone goes into low battery mode: it still functions, but the screen goes dim, and some of the apps start shutting down to conserve energy. Only in the case of your body, those “apps” are your organ systems, like your reproductive and endocrine systems!

What Are the Impacts of LEA?

Prolonged LEA can have serious consequences on your health. One of the most notable consequences is on your reproductive system. Many women still believe that it’s “normal” for female athletes to lose their periods when they train. It is far too common. But it is NOT normal! Research shows that when women dip into LEA, it disrupts the production of luteinizing hormone, which plays an important role in ovulation and regulating the menstrual cycle. 

One of the downstream consequences of disrupting your hormones with LEA is serious and potentially lasting negative impacts on your skeletal system. Without enough energy, your osteoblasts (the cells that build bone) and osteoclasts (the cells that break down and resorb bone) can’t do their job properly, and you end up breaking down more than you build up. The end result is bone stress injuries and stress fractures, as well as an increased risk for osteoporosis down the line.

LEA also can lead to a host of other health disruptions, including irritability, bouts of depression, brain fog, depressed immunity, loss of libido, GI issues like constipation and diarrhea, and can lead to nutritional problems like anemia

It can also interfere with muscle growth. Recent research on 30 active, naturally menstruating females reported that when they trained (endurance and resistance) with LEA for 10 days, they experienced impaired myofibrillar and sarcoplasmic muscle protein synthesis, compared to when they were training with optimum energy availability, which the researchers defined as 50 kcal per fat free mass (FFM) per day (more on how to calculate that in a bit). They also observed reductions in lean mass, urinary nitrogen balance, free androgen index, thyroid hormone concentrations and resting metabolic rate following LEA. The researchers concluded that LEA may have negative consequences for skeletal muscle adaptations.

It seems obvious that LEA can also hurt your performance. But here’s the problem: depending on your sport, you might not see decrements, and may even see some improvements, for a period of time, because remember, LEA is about not having enough energy left over after training, not for training per se. So though chronic LEA negatively influences muscular adaptations and muscle protein synthesis, research shows that it may fly under the radar for prolonged periods of time before adaptations stagnate and performance declines. Worse, you may already be damaging yourself, such as bone loss, before you reach that point. 

How to Spot LEA

It’s important to try to spot LEA before it becomes a serious health problem. Some telltale signs that you are in low energy availability include:

  • Irregular or missing menstrual cycles
  • Fatigue
  • Mood problems, including irritability and depression
  • Frequent illness
  • Frequent injuries, especially stress reactions, and fractures
  • Decreased libido
  • Increase in GI issues
  • Poor or decreased training adaptations

How to Get Out of & Avoid LEA

This is the tricky part. There are many reasons female athletes find themselves in a state of LEA. Some are intentional, such as dieting and restricting carbohydrates. Others are unintentional–women think they’re eating enough, but they’re not. And most often, they are not eating in and around training; if you delay food intake after, your body stays in a catabolic (breakdown) state, and your brain registers this as not having enough energy to support adaptation as well as health.  If you have disordered eating, a history of restrictive eating, or an outright eating disorder, working with a professional should be your first step. 

How can you check if you’re dipping into LEA, even if unintentionally? If you know your body composition, you can start with using the equation for determining energy availability (EA), which is your dietary energy intake (kcal) minus your exercise energy expenditure (kcal) divided by your fat free mass (FFM) in kilograms (kg). You want the final number (EA) to be over 45 calories per kilogram of FFM; 50 calories per kilogram FFM is a good number to aim for if you train regularly. Anything less than 30 calories per kg is defined as LEA, and at that point you start experiencing health risks after only five days.

An active 64kg/140lb female who is 19% body fat and burns about 400 calories a day at the gym would need to eat about 2,800 calories a day to be above that 45 calorie/kg FFM benchmark. If that sounds high, it’s because you’ve been conditioned to believe that women should be limiting themselves to 1200 calories a day–a harmful diet-culture message that has absolutely no bearing on active or athletic women. 

Realistically, I know that many women, even with the best of intentions may fail to hit those EA marks. That’s why it’s important to be very cognizant that you are refueling after your training, within 30-45 minutes, to stop the brain from perceiving low energy intake. It’s also important to be sure you’re not going low-carb/keto, because, as research shows, getting adequate carbohydrates may help you avoid LEA even during those times when your EA is lower than is optimum.

Though I don’t generally advocate rigidly counting calories and/or tracking macros, it is worth it to keep a tally for three to five days to see how much energy you’re actually taking in versus how much you think you’re taking in. Chances are, you’ll be very surprised!

The next step is increasing your intake around your training, and then across the day, see how you feel and perform when you’re hitting the mark. Again, I bet you’ll be surprised. So many of my athletes reach their optimum performance potential once they finally achieve their energy needs. 


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