We need to talk about RED-S

As a talented young racer who could win sprints but struggled over climbs, Kaia Schmid thought cutting weight by dieting and training extra hard would be the key to success. She became obsessed with a protein-heavy, low-carb diet. This made her fatigued. She actually got slower on the bike. She bonked more often. She put out worse sprint numbers. And eventually, she lost her period. The opposite of what Kaia was hoping for ended up happening. She didn’t know it at the time, but she was not alone in going through this.

Cutting weight is a fixation for many athletes and cyclists more than most. Being lighter is seen as a sure route to better performance. Skinny arms are worn like a badge of honour in the pro peloton, but it is extremely dangerous, and can lead to symptoms like Schmid experienced.

This obsession with being ‘light’ or ‘lean’ is pervasive in professional sports, but especially in endurance disciplines. It cuts across men’s and women’s athletics, too.

“A lot of people struggle with it,” says Schmid. “That’s why it was so easy to be sucked into the mindset. Once I did become aware of the foods that I was eating, it quickly turned into an obsession and I think that’s how it turns out for a lot of people in the sport.”

Because losing her period was associated with being skinnier, in Schmid’s mind getting her period became associated with being overweight.

“Even though I knew objectively that getting my period was healthy, in my head I was like – Oh no, this means that I’m getting chubby.”

But why did a healthy young woman lose her period in the first place?


Schmid began to research what she was going through, and discovered that her battery of symptoms was likely because her carbohydrate and calorie intake had plummeted below the energy demand that her intense training required. She was experiencing Relative Energy Deficiency in Sport, or RED-S. She had lost her period because her body did not have enough energy to produce estrogen.

RED-S can be very difficult to diagnose, because it has a wide array of symptoms, many of which are initially approached in isolation. By devoting their attention to just one symptom, clinicians sometimes miss the bigger picture. Namely, low energy availability due to caloric imbalance from too much exercise and not enough nutrition.

In the 2018 IOC RED-S Consensus Statement Update, the report posited that 10% of athletes will experience RED-S in their career. Thorne’s Laura Kunces, PhD, RD, says that’s 10% too many.

“It should be very well known that if you lose your period that’s not good. Otherwise, you’re left with lots of people like Kaia and others thinking they should just keep going. RED-S can also affect men and it is probably considered a taboo subject, but I think in many instances it’s just a lack of education in nutrition 101.”

Kunces also emphasises the difference between being racing fit, and being as light as possible. “Getting into racing shape does not mean getting lean, it means strengthening the body to perform day after day, week after week for these races.”

Schmid initially thought that losing her period was the relatively harmless but necessary price of being a pro cyclist. She admits that the fixation on that word ‘lean’ led her down a dark path. “I just wanted to focus on being lean, and getting my period was, in my mind at least, a sign of not being lean enough.”

In fact, the effects can be devastating. Women who lose their period often develop osteoporosis, and this loss of bone density can be irreversible. The risk of infertility and problems with pregnancy are also increased. If you don’t ovulate and don’t have periods, you can’t become pregnant. When hormone imbalance is the cause of lost periods, this can also cause miscarriage or other problems with pregnancy.

As well as losing her period, RED-S gave Schmid a weakened immune system and hurt her sleep. She says she’s “lucky” not to have been impacted by osteoporosis.


RED-S is a deficiency, so the first thing athletes affected by it need to do is redress the balance. Either by getting more energy in, or reducing the amount of exercise they are doing. For professional athletes like Schmid with a heavy training and heavy racing load, the latter is difficult. One solution is to focus on boosting that caloric intake.

With the support of Thorne’s nutrition experts and Human Powered Health Cycling’s team doctors, she went from “going to bed hungry and waking up hungry”, to eating high-quality carbohydrates and protein sources every two hours throughout the day with a serving size similar to a deck of cards. That meant eating plenty of nuts, milk, chicken and yogurt, as well as some good fats to aid nutrient intake.

Kunces was on hand to help Schmid through the process. “We took a holistic approach. Thorne is a food-first company and supplements are there to fill the gaps and to help people who have these extra high needs. We talked about how, before a hard training ride, we can fit things into her jersey pockets that are nutritious.”

Of course, a bigger cultural change is also needed to help protect young athletes like Schmid from going through the same experience. The fixation on weight needs to switch to a prioritisation of the right fuels for a high-performing body, and that means better education.

“I think if I had talked to somebody sooner I might have been able to get on top of it sooner,” reflects Schmid. “I wish the national team and trade team had more talks about it and raised more awareness about the issues.”

Coaches, too, need to be knowledgeable about RED-S and able to pre-empt its rise. “I think if coaches, male and female, were on top of RED-S, it could be dealt with before people actually go through it.”

Now, Schmid is eating healthier food more consistently and in larger amounts, and doing better ‘numbers’ on the bike as a result. She is also working closely alongside her personal nutritionist Judith Haudman. She has made incredible progress on her journey. That doesn’t mean RED-S has disappeared entirely. But she is now managing it in a healthy way.

“To say that I’m not struggling anymore would be a lie. It’s something that I will deal with throughout my career. Luckily I have the right tools now to fight it.”

A selection of supplements from Thorne that help to support athletes during their period.

Amino Complex – Losing one’s period can lead to a reduction in bone and muscle density. Amino Complex provides a vital building block for reversing that trend.

Magnesium Bisglycinate – Sleep is one of the most heavily impacted facets of life for athletes with RED-S. Magnesium Bisglycinate helps active individuals to unwind.

RecoveryPro®  – RecoveryPro®, which is taken at night, gets valuable protein back into the body, and helped Kaia fend off the feeling of ‘going to bed hungry and waking up hungry’.

Words By

Tom Owen

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