Low Energy Availability (LEA):

What is LEA?

LEA occurs when an individual’s energy intake is insufficient to support the body’s functions after accounting for energy expended in exercise.

It’s essentially an energy deficit that can occur in both athletes and non-athletes.

It’s calculated as energy intake minus exercise energy expenditure, relative to fat-free mass. This can be a complex calculation involving a lot of monitoring but there is a simple explanation further below.

LEA can occur even when total calorie intake seems adequate, if exercise energy expenditure is high. It can lead to various physiological and performance issues, including REDs which we will discuss in the next post.

It can, paradoxically, lead to weight gain in some cases. This is most commonly seen in women and is definitely something active women should be aware of if they cut calories and or/up the activity levels.

Weight Gain

Consuming less calories and then gaining weight might seem counterintuitive, but there are several mechanisms through which this can occur:

Metabolic Adaptation:
Chronic LEA can cause the body to lower its metabolic rate to conserve energy.
When normal eating resumes, this lowered metabolism can result in weight gain.

Hormonal Changes:
LEA can disrupt hormonal balance, particularly affecting thyroid hormones and cortisol.
These hormonal changes can lead to increased fat storage and water retention.

Increased Appetite:
After periods of restriction, the body may signal increased hunger, leading to overeating.
This can result in rapid weight gain, often exceeding the original weight.

Changes in Body Composition:
LEA can lead to loss of lean muscle mass.
When weight is regained, it’s often in the form of fat rather than muscle, changing body composition.

Insulin Sensitivity:
Prolonged LEA can affect insulin sensitivity, potentially leading to increased fat storage when normal eating resumes.

Disrupted Hunger and Fullness Cues:
Chronic undereating can disrupt natural hunger and fullness signals, making it harder to regulate food intake.

Psychological Factors:
The stress of restrictive eating can lead to binge eating episodes, contributing to weight gain.

Edema:
In some cases, especially when LEA is severe, the body may retain water, leading to temporary weight gain.

Rebound Effect:
When energy intake is increased after a period of LEA, the body may overcompensate by storing extra energy as fat.

It’s important to note that while LEA can sometimes lead to weight gain, the primary concern should be overall health and performance rather than weight alone.

All Impacts of LEA

Physiological impacts:
Metabolic rate reduction
Bone Mineral density decrease
Impaired protein synthesis
Cardiovascular changes; i.e. lower heart rate, blood pressure
Hormonal disruptions; i.e. decreased estrogen, testosterone

Psychological impacts:
Increased irritability
Difficulty concentrating
Depression
Anxiety

Performance impacts:
Decreased endurance
Reduced muscle strength
Increased injury risk
Impaired training adaption

Addressing LEA involves gradually increasing energy intake to support bodily functions and athletic performance, which may or may not result in weight changes.

How to calculate LEA

LEA is defined as dietary energy intake minus exercise energy expenditure, normalized to fat-free mass (FFM).
The formula is: Energy Availability = (Energy Intake – Exercise Energy Expenditure) / Fat-Free Mass.

The Thresholds are:
Optimal energy availability: >45 kcal/kg/FFM/day
Reduced energy availability: 30-45 kcal/kg FFM/day
Low energy availability: <30 kcal/kg FFM/day

Let’s look at an example of someone weighing 70 kg with 20 body fat%

Step 1:
Calculate Fat-Free Mass (FFM):
Body Fat Mass = 70 kg × 20% = 14 kg
Fat-Free Mass (FFM) = 70 kg – 14 kg = 56 kg
Step 2:
Energy Availability (EA) Calculation EA = (Energy Intake – Exercise Energy Expenditure) / Fat-Free Mass

For our 56 kg FFM individual:
Optimal EA threshold: 56 kg × 45 kcal/kg = 2,520 kcal/day
Low EA threshold: 56 kg × 30 kcal/kg = 1,680 kcal/day

Example scenarios:

A. Optimal EA: Energy Intake: 3,000 kcal Exercise Energy Expenditure: 400 kcal EA = (3,000 – 400) / 56 = 46.4 kcal/kg FFM/day (Optimal)

B. Reduced EA: Energy Intake: 2,500 kcal Exercise Energy Expenditure: 600 kcal EA = (2,500 – 600) / 56 = 33.9 kcal/kg FFM/day (Reduced)

C. Low EA: Energy Intake: 2,000 kcal Exercise Energy Expenditure: 800 kcal EA = (2,000 – 800) / 56 = 21.4 kcal/kg FFM/day (Low)

These calculations demonstrate how increased exercise energy expenditure or decreased energy intake can lead to reduced or low energy availability, even when total calorie intake might seem adequate.


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