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Are You Meeting Your Fuel Needs?Impact of Relative Energy Deficiency (RED-S) on Health & Performance

Relative energy deficiency in sports (RED-S) occurs when an athlete has insufficient energy intake relative to their amount of training and energy expenditure over a period of time. RED-S can be detrimental to performance and health, including injury, eating disorders, etc.

Being alive takes energy. The amount of energy it takes for your body to be at rest is known as the Basal Metabolic Rate (BMR). For athletes, training requires more energy and thus more calories.

As swimmers, we are greatly concerned with making sure we are getting enough adequate fueling. Swimming is an endurance sport, which, also requires a lot of strength and speed. Swimming requires athletes to eat lots of calories to be able to sustain their high intensity training schedules year round.

RED-S occurs when athletes are consistently not meeting their energy needs to balance energy expenditure. Low Energy Availability (LEA) can cause metabolic rate to slow to conserve calories. The hormonal changes will signal the body to increase body fat and decrease muscle. Therefore, it becomes increasingly difficult to lose weight or change body composition in LEA, which the athlete may interpret as not restricting enough or training hard enough. In other words, it’s very easy for a vicious circle to develop. LEA in males is more likely to go unnoticed. Female symptoms can be a little more obvious with the menstrual cycle being disrupted. Regular menstration is a sign of hormones being at a healthy level.

Some of the negative health consequences of underfueling (LEA) include:


Menstrual Dysfunction (W)

Bone Health

Endocrine Function



Growth & Development




Health being affected can also have a negative impact on performance.

Some negative performance consequences that can occur include:

Decreased Glycogen stores

Decreased endurance performance

Increased injury risk

Decreased training response

Impaired judgment

Decreased coordination

Decreased concentration



RED-S can occur in athletes of any age or at any level within their sports. Young athletes and dancers (and other aesthetic sports) are potentially at a greater risk of developing RED-S as puberty is already a high-energy demand state.

There are three factors under athlete control that can help prevent RED-S.

1. Training load

2. Nutrition

3. Recovery

Integrating periodization of these key factors will need careful guidance from a coach and ideally a clinical dietician!

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