Low Testosterone Caused by Energy Deficiency In Sports

Written by Ben Bunting: BA, PGCert. (Sport & Exercise Nutrition) // British Army Physical Training Instructor // S&C Coach.


Men with low testosterone levels may suffer erectile dysfunction and be unable to produce sperm effectively, or may develop breast tissue known as gynecomastia, known as male breastenecomastia.

Relative Energy Deficiency Syndrome (RED-S), also referred to as the Female Athlete Triad, affects athletes of all genders, ages and levels of competition.

It's characterized by poor energy intake that results in muscle atrophy, bone densification and decreased hormone production.

Relative Energy Deficiency in Sport

Relative Energy Deficiciency, or RED, in sport is often overlooked yet complicated and dangerous condition which affects not only athletes' health and performance but also the health and performance of all stakeholders involved.

It stems from an imbalance between energy intake and expenditure; an illness-like state caused by insufficient intake relative to expenditure.

RED-S affects multiple body systems including metabolism, menstrual function, bone health, immunity and protein synthesis and can have long-term consequences without early diagnosis and identification.

RED-S is most often associated with female sports participants, but also frequently appears among male and recreational athletes.

Formerly referred to as the Female Athlete Triad, however, due to RED being present among both genders and its impact being proven beyond just three areas of women's health it now more appropriately known as RED-S Clinical Assessment Tool (CAT).

Female athletes most often identify RED-S through changes in ovulation or period patterns. Missed or irregular periods are an early indicator that more serious problems exist.

Other symptoms of low Energy Availability could include fatigue, irritability, low immunity levels, muscle or bone injuries, decreased sleep quality and psychological strain.

Low energy availability is usually at the root of these symptoms and is the result of eating too few calories. Athletes who engage in intense training sessions while restricting their dietary intake in an effort to reach specific training goals (like weight loss) are at greater risk for RED-S.

During a training session, red can cause muscles and cardiovascular systems to fatigue more quickly, leaving less energy available for recovery.

Athletes with RED-S are at an increased risk of injury as their bodies have less ability to repair sprains, strains and stress fractures sustained during intense workouts.

If an athlete exhibits signs of RED-S, it is imperative that they seek care from a sports medicine specialist who takes an holistic approach and recognizes that there is no set formula for balancing health and performance.

When making treatment decisions, these physicians will take into account factors like diet, training requirements and restrictions as well as any dietary needs or restrictions specific to each athlete.

For athletes to avoid RED-S, they must consume sufficient calories in the days leading up to and following training sessions, especially in the days prior to and post workout.

They should aim to include foods rich in carbs, fat and proteins into their diet as well as calcium and vitamin D to maintain bone health.

They should limit high impact exercise while practicing good recovery habits so their bodies have time to recover after training sessions.

Additionally they could consider using a RED-S CAT test in order to assess whether low energy availability exists within them and develop an appropriate treatment plan accordingly.

Energy Deficiency in Sport Reduces Testosterone

Relative Energy Deficit in Sport (RED-S) occurs when athletes consume less energy than they expend through exercise which poses serious health risks and can drastically diminish peak performance.

Furthermore, abnormal endocrine function caused by inadequate nutritional intake has several side effects that include disordered menstruation and low bone density.

Athletes experiencing Red-S Syndrome are likely to experience irregular periods, low bone density and testosterone levels that drop below optimal.

Furthermore, their risk for osteoporotic fractures increases. Athletes in Red-S syndrome also tend to have lower resting metabolic rates. Their bodies prioritizing basic functions over maintaining other systems like bone tissue and muscle development.

This is particularly problematic in sports like distance running, gymnastics, basketball and swimming that involve frequent impact such as skydiving or climbing.

Birkedal Stenqvist conducted a recent analysis using data from the Norwegian Sports and Exercise Science Survey (NSE) to identify factors contributing to RED-S in male athletes.

His research revealed that RMR ratio is the strongest predictor of male RED-S, both age and training load playing a part.

A low RMR ratio signifies an athlete is consuming significantly less than required to meet energy needs - something particularly prevalent among younger men.

Men who suffer from RED-S are affected by factors like low protein intake, elevated ghrelin and leptin levels and abnormal insulin, growth hormone and thyroid function.

This impairs their glucose metabolism by elevating free fatty acids and ketones while impairing muscle protein synthesis. Furthermore, an imbalance can develop with respect to diet containing more saturated than monounsaturated dietary fats.

Although this study has some restrictions, such as its cross-sectional design limiting causal claims and participants self-reporting their food and exercise habits, it remains an immensely valuable contribution.

It will increase our knowledge about RED-S' effects on health, athletic performance and physique; its prevention/treatment; as well as providing insight into its prevalence among elite male athletes. This area of research must continue.

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Does Relative Energy Deficiency in Sport Reduce Testosterone in Men?

Human research on exercise and hormones has been ongoing since the early 1970's (although animal based studies predate this significantly).

However, there remains little understanding of the complex relationship between an athlete's energy intake and performance; particularly male athletes.

With the recent introduction of "relative energy deficiency in sport", or RED-S, by the International Olympic Committee in 2014 to raise awareness that male athletes may also suffer from this condition which doesn't just impact female competitors but can affect all levels of competition as well.

Red-S occurs when an athlete does not consume sufficient calories to meet their training and competition demands, due to disordered eating behaviors, weight loss diets, excessive exercise or lifestyle choices such as disordered dieting.

Athletes who fail to consume sufficient energy often suffer health and performance consequences due to low energy availability such as menstrual dysfunction, decreased testosterone, bone loss or increased injury risk

This phenomenon is most pronounced among combat athletes, rowers and jockeys due to weight classification categories in their sport putting them in deficit situations.

Studies have demonstrated that RED-S can significantly decrease testosterone in both young and older, recreational and elite athletes alike.

Testosterone plays an essential role in muscle growth and bone health; its depletion could cause decreased strength, power, lean body mass and higher cortisol levels (which acts as a stress hormone).

Blood and saliva tests can detect various types of testosterone found in the body, with total and free testosterone as well as sex hormone binding globulin tending to decline with prolonged high intensity exercise due to energy shortage.

Though there could be numerous reasons behind this reduction, one major cause may be decreased available energy to supply your cells' needs due to increasing exercise intensity.

Lower energy availability to working muscles causes a reduction in their size and strength, which may increase fatigue during exercise more rapidly and hinder recovery, increasing overtraining risks as well as chronic fatigue risks.

It may also reduce an athlete's ability to repair sprains or strains effectively which increases injury risks; hence the importance of keeping to a nutritious, balanced diet for athletes.

Testosterone Deficiency

Testosterone is essential to both male and female reproductive health. Additionally, testosterone helps athletes build and maintain muscle by acting as a natural anabolic agent and maintaining optimal levels.

When testosterone levels decline too far below optimal, erectile dysfunction may occur while athletes suffering from reduced performance may suffer fatigue, poor recovery rates and reduced fat-free mass. Furthermore, losing testosterone could decrease bone density levels significantly.

Athleticians experiencing a decrease in performance that cannot be explained otherwise should consider low testosterone as a potential culprit.

Low testosterone can be caused by various factors, including long-term anabolic steroid use, pituitary gland tumor or surgery, chronic opioid use, sleep apnea and certain medications.

Alternatively, it could be caused just simply by getting older as your body produces less testosterone naturally.

Lifestyle changes may be the key to treating low testosterone levels, with healthy diet and regular physical activity often providing essential components of hormone production in your body. Exercise also plays an integral part of this strategy.

Alternative approaches for treating low testosterone levels include oral therapy (swallowing capsules) and intramuscular injections, administered directly into muscle.

Testosterone skin gels may also be applied topically on arms, shoulders or thighs by either yourself or through provider assistance.

Blood tests can assist the doctor in diagnosing secondary or primary hypogonadism in patients, with levels of luteinizing hormone and follicle-stimulating hormone, which could either indicate one condition or the other; furthermore, prolactin levels could indicate pituitary gland problems.


RED-S reduces testosterone by suppressing resting metabolic rate (RMR), an essential source of energy for muscle cells.

Suppressing RMR causes energy reserves for muscles to decline; consequently, their performance may suffer and their muscle mass reduce.

This may negatively impact sports performance for athletes attempting to increase power-to-weight ratios or shed body fat.

The Sigma Statement and Relative Low Energy Deficiency in Sport (RED-S) has become an increasingly popular movement within endurance sport to educate athletes and their support teams about the effects of intentional or accidental underfueling.

While this is good news, it must also be remembered that male athletes need to address underfueling just like any other issue related to fueling; consequently, female athlete triad has been replaced with relative Low Energy Deficiency in Sport (RED-S).

The Sigma Statement and RED-S are terms used to refer to an umbrella syndrome of poor health and declining athletic performance that occurs when athletes do not consume sufficient energy from food sources to sustain normal physiological function after accounting for energy expended during exercise.

Impairments to function include changes in menstruation, bone health and immune function - as well as impaired ovulation/missed periods associated with the female athlete triad.

How Does Relative Energy Deficiency in Sport Reduce Testosterone?

When athletes fail to consume sufficient calories to support their health and performance, it can have serious repercussions for both themselves and their sport.

Once known as the Female Athlete Triad (FAT), now known as Relative Energy Deficiency in Sport (RED-S). This more inclusive model broadens its scope. A

ny athlete regardless of gender or training intensity could experience relative energy deficiency, though combat sports and rowers tend to experience higher rates due to a focus on body weight pre-competition (i.e. pre-competition).

Chronic energy deficiency reduces resting metabolic rate (RMR), diminishing fuel for movement and other physiological functions, hampering recovery, and leading to an infinite cycle of energy deficit, increased hunger, decreased food intake and further reduced RMR.

This may have detrimental impacts on bone health, menstrual function and testosterone levels for both women and men, along with possibly impacting on stress hormone glucocorticoid production levels.

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