Athletes From Every Sport Are Talking About ‘RED-S.’ Is Workout Hustle Culture to Blame?

YOU NEED TO fuel your body properly for peak performance—that's not news. But hitting the right balance of fuel to energy output can be tough, especially if you're trying to lose weight in the process, are on a GLP-1 medication, and/or recently switched up your workouts. That's where you fall into danger of RED-S, a scary sounding condition where your body reaches a dangerous stage of energy depletion

Also known as “Relative Energy Deficiency in Sport,” RED-S can do everything from slow down your progress to mess with your body on a cellular level. "The simplest explanation is it's an energy mismatch," says Albert Matheny, RD, CSCS, co-founder of SoHo Strength Lab.

RED-S has always been a potential issue with athletes, but the rise of GLP-1s and a NO DAYS OFF workout hustle culture has pushed the condition into the fore.

Trainers say every active person should know the symptoms of RED-S—and what might cause them to show up.

What is RED-S?

RED-S HAPPENS WHEN you're not fueling your body properly. "It essentially means running your body's engine on empty," explains Dani Singer, CPT, founder of Fit2Go Personal Training. "It's a mismatch between the energy you take in through nutrition and the energy you expend through exercise and daily living."

While a slight calorie deficit is needed to lose weight, RED-S is more severe than cutting a few calories. It's chronically under-fueling while also trying to train at a high level. "You are demanding a level of output from your body that you aren't giving it the fuel to sustain," Singer says.

What can happen with RED-S?

A FEW THINGS can go down. "Deep, lingering fatigue is usually the first red flag," Singer says. "You'll feel like you're moving through molasses." At the same time, because your body isn't dedicating energy to recovery, Singer says you become "highly susceptible" to overuse injuries and stress fractures due to decreased bone mineral density.

"You'll also likely see thermoregulation issues—always feeling cold—compromised immunity, hormonal imbalances, and ironically, a complete plateau in your fitness progress," Singer says. "You can't build muscle or acquire new physical skills if your body doesn't have the building blocks to do so."

With RED-S, your body does what it can with reduce energy it has. "It really prioritizes key metabolic functions and the things that require your body to function [in daily life]," Matheny says. He compares RED-S to being in low power mode—your body is going to try to support basic functions, while forgetting about things like muscle growth and fitness performance.

"We are constantly taught that 'eat less, move more' is the holy grail of fitness, but your body needs energy not just to exercise, but to simply keep the lights on for things like breathing, hormone production, and cellular repair," Singer says. "When you severely under-fuel while keeping your physical output high, your body goes into triage mode."

What's fueling RED-S?

THERE ARE LIKELY a few things behind this. "For the general fitness population, it often comes from a toxic combination of diet culture and high-intensity workout trends demanding maximum output on minimum calories," Singer says.

And then there are GLP-1s. "These medications are incredibly effective at blunting the natural hunger cue," Singer explains. "A user might only be taking in 800 to 1,000 calories a day simply because they feel completely full." If someone on a GLP-1 decides to pair their weight loss journey with a rigorous new workout routine, they may not realize how little fuel is in the tank, Singer says.

How to determine the best fueling and recovery process for you

BECAUSE EVERY PERSON’S energy needs are different, avoiding or finding a solution to RED-S can be complex. "The threshold in literature is 30 calories per kilogram of body weight—that's the lowest level," Matheny says. (That means a 180-pound man should be taking in 2,448 calories per day at a minimum.)

Singer also recommends flipping the way you look at food. "We have to stop viewing food purely as a metric to minimize and start viewing it as fuel for the capabilities we want to build," he says. Singer suggests being "brutally honest" with your baseline food intake, making sure you're eating enough to support your activity.

"From there, listen to the biofeedback your body gives you," he says. "If you are constantly exhausted, sore for days after a basic workout, or losing your motivation to train, you are likely under-fueled." Singer recommends prioritizing protein for recovery, along with getting in enough carbs to fuel the work you're asking of your body. "A good routine should improve how you move and feel in daily life, not break you down," he says.

If you're struggling to get the balance right, consider talking with a sports-minded registered dietitian. They should be able to help you figure out what you're going wrong and put you on the path to fueling your body properly in the future.