What is RED-S?

Relative Energy Deficiency in Sports, or RED-S, is “impaired physiological functioning caused by a relative energy deficiency and includes, but not limited to, impairments of metabolic rate, menstrual function, bone health, immunity, protein synthesis, and cardiovascular health”. The main cause of RED-S is low-energy availability (LEA). LEA can be a result of low calorie diet, excessive training, and inadequate rest.

If an athlete reaches LEA, their body taps into stored energy, like muscle and fat. Our body also breaks down bone for minerals. It is myth that when people follow a low-calorie diet their body automatically starts burnign fat for fuel. While in reality, our body wants to chose the least energy-costly way to make glucose for fuel. It costs a lot of energy to turn fat into energy that a cell could use. On the other hand, certain amino acids (the building blocks of protein), can be turned into glucose pretty easily. So, our body will do that before burning fat.

So why is this bad? Because, our body will break down lean muscle mass to harvest these amino acids. As well as redirect protein from our diet to turn into glucose. And as a result, dietary protein is no longer available to maintain lean muscle mass, or build new muscle for that matter.

Consequences of RED-S

Over time, the symptoms of RED-S begin surface such as females losing their mentrual cycle, decreased bone density, low energy, increased soreness, mood swings, easily plucked hair, dry and cracked skin, and of course weight loss. And again, these symptoms are a result of the body not having enough energy. Having limited energy can affect every system in the body. From general growth and development, the cardiovascular system, the digestive system, the immune system, and an individual’s metabolic rate.


The Female Athlete Triad

The Female Athlete Triad is when a female athlete experiences 1) RED-S, 2), loss of her menstrual cycle, and 3) decreased bone density at the same time. The Female Athlete Triad has been a concern for professional sports for decades. But treatment is focused on reversing the Triad rather than preventing it. For both RED-S and The Female Athlete Triad, there is an increased risk of injury, osteoporosis, digestion issues, reduce heart rate and arrhythmias, as well and an increased risk of depression and/or developing a serious eating disorder.

Males are not excluded from RED-S, and even not excluded from some symptoms seen in the Female Athlete Triad. Research is seriously lacking in the study of RED-S focusing in the male athlete population. From what research is available, it has shown that males can fall victim to low energy availability as well, especially men who participate in cycling and weight class sports. It is crucial to recognize the fact that male athletes can have disordered eating behaviors and need just as much support and professional help as females who suffer.


An individual calorie recommendation can be prescribed after working closely with a Registered Dietitian and assessing the individual’s medical history and activity levels.


Focus on RED-S Prevention

Why is this important? Again, low-energy availability (LEA) can have serious long-term consequences on an athlete’s health, while also impairing performance. If he/she is not consuming enough fuel for a long period of time, it is possible they will no longer be able to compete in their respective sport. If you suspect that you or a loved one may have RED-S, you should seek help. A registered dietitian nutritionist who has a knowledge in sports nutrition will be able to assist you with your nutrition needs. An RD will be able to screen a client for RED-S, as well as assess any potential disordered eating patterns. By coming to nutrition appointments, an athlete will learn how to build their relationship with food to increase athletic performance and confidence.

Call our office at 301-474-2499 to book an appointment with our registered dietitian.


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Rebecca Bitzer loves to empower Registered Dietitian Nutritionists (RDNs) and their clients.  Co-author of Welcome to the Rebelution: Seven steps to the nutrition counseling practice of your dreams and  Taste the Sweet Rebellion: Rebel against dieting.