Low energy availability — not eating enough to support your activity level — is more common among active people than many realize.
This article summarizes the concept so you understand what low energy availability is, recognize key warning signs, and know practical steps to stay properly fueled.
What is Low Energy Availability?
Low energy availability (LEA) occurs when the calories you consume are insufficient to support both your body’s basic physiological functions and the energy expended during exercise. In other words, energy is being used for workouts but there isn’t enough left to sustain fundamental processes like cell repair, circulation, respiration, digestion, and hormonal balance.
Your daily energy expenditure typically includes:
- Basal metabolic rate (BMR) — energy required for essential cellular processes
- Non-exercise activity thermogenesis (NEAT) — energy from everyday movement, fidgeting, and chores
- Exercise activity thermogenesis (EAT) — energy used during planned exercise
- Thermic effect of food (TEF) — energy needed to digest and metabolize what you eat
What are Signs of Low Energy Availability?
Signs that your energy intake may not match your activity level include, but are not limited to:
- Decreased athletic performance
- Reduced strength or prolonged plateaus
- Excessive or prolonged muscle soreness
- Menstrual irregularities or missed periods
- Frequent injuries or slow recovery
- Irritability, mood changes, or anxiety
- Difficulty concentrating or brain fog
- Persistent fatigue or lack of energy
- Loss of motivation for movement or training
- Lowered bone density over time
These signs can appear subtly and develop over weeks or months, so monitoring trends in how you feel and perform is important.
How is Low Energy Availability Related to RED-S?
Chronic low energy availability is the underlying cause of RED-S (Relative Energy Deficiency in Sport). Historically, the Female Athlete Triad described a link between low energy availability, menstrual dysfunction, and low bone density. RED-S expands this model: it affects both men and women and can disrupt reproductive hormones, bone health, metabolism, cardiovascular function, immune response, and psychological well-being.
Who Can Have Low Energy Availability?
Contrary to popular belief, you don’t have to be an elite athlete to be at risk. Any person who consistently consumes fewer calories than needed to cover both basal needs and exercise expenditure can develop LEA.
Research has shown that even recreational exercisers can be affected; one study found that nearly half of female recreational exercisers were at risk for low energy availability.
Common contributors include pressure to be leaner, intentional weight loss, restrictive diets, eliminating whole food groups without medical reason, or adopting well-intentioned eating trends that unintentionally reduce calorie intake. For example, replacing calorie-dense carbohydrate sources with lower-calorie vegetables is healthy in many ways but can reduce total energy intake if not compensated elsewhere.
How Do You Avoid Low Energy Availability?
You can train hard and pursue performance goals—absolutely. The key is fueling appropriately so your body can meet both exercise demands and baseline physiological needs. Practical strategies include:
- Eat regular meals spread across the day to maintain energy balance.
- Include a balance of protein, carbohydrates, and healthy fats in meals to support recovery, hormone health, and sustained energy.
- Add a pre-workout snack or post-workout meal when training intensity or duration increases to support performance and recovery.
- Monitor performance, recovery, mood, and menstrual function as early indicators of inadequate fueling.
- If you notice signs of disordered eating, severe restriction, or persistent menstrual changes, seek help from a qualified health professional or registered dietitian experienced in sports nutrition.
Fueling, training, and recovery should be guided by evidence-based practices to protect long-term health and performance.
For structured guidance, consider working with qualified coaches or registered dietitians who specialize in sports nutrition and energy availability.
Learn More About Fueling
If you want to dive deeper into how to fuel for activity and avoid low energy availability, look for reputable sources such as peer-reviewed research or experts in sports nutrition and physiology. Podcasts, educational episodes, and evidence-based articles can be useful resources to expand your understanding.
References
(1) Logue, et al. 2020. Low Energy Availability in Athletes 2020: An Updated Narrative Review of Prevalence, Risk, Within-Day Energy Balance, Knowledge, and Impact on Sports Performance.
(2) Wasserfurth, et al. 2020. Reasons for and Consequences of Low Energy Availability in Female and Male Athletes: Social Environment, Adaptations, and Prevention.
(3) Mountjoy, et al. 2014. The IOC consensus statement: beyond the Female Athlete Triad—Relative Energy Deficiency in Sport (RED-S).
(4) Slater, et al. 2016. Female Recreational Exercisers at Risk for Low Energy Availability.