Trying to get fitter? You might actually need to eat more

“RED-S is when there’s not enough energy to support all movement and biological processes,” says McGregor.

“It’s further impacted by internal stress on the body, such as not fuelling enough, losing weight rapidly and training at too high intensity with little or poor recovery.”

It can lead to other health issues too.

“Often we’ll see low iron levels in individuals who are in RED-S,” says McGregor.

“Under-fuelling can also lead to disruptions in female hormones which can lead to irregular or even loss of periods.

“If you don’t have regular menstrual cycles, this starts to have a negative impact on other areas of your health and can lead to injuries such as stress fractures, external.”

Davis says losing your period was historically considered the norm in athletes:

“It used to be seen that if you lost your period, it meant you’re training hard. Now, we know, losing your period is a key sign of under-fuelling. It’s a sign you need to pull back.”