A mismatch between the number of calories consumed and the amount of energy expended may be harming the health of some sportspeople, and not only those who compete at an elite level. Relative energy deficiency in sport (Reds) was first recognised by the International Olympic Committee in 2014 and a panel of international experts is continuing to scrutinise the latest science to improve diagnosis and prevention.
The concept of Reds developed from the “female athlete triad”, a combination of menstrual dysfunction, low energy and weakened bones seen in young female athletes who are exercising hard and not eating enough. The newer term recognises that the problem goes further.
“We were quite worried about the effects on male athletes and also felt there were more outcomes from low energy availability than just bone and menstrual dysfunction,” says Australian sports dietitian Louise Burke, one of the authors of a new consensus statement on Reds, published in the British Journal of Sports Medicine.
Over the short term, not eating enough to fuel an active body isn’t necessarily something to worry about. “In some cases, you want it to happen,” says Burke. “It’s useful for an athlete to change their body composition at times and it’s useful to train hard and increase the volume of training. Small periods of low-energy availability may not be problematic.”
However, prolonged periods of not eating enough to support the training being done risk more serious effects. The degree to which this might be a problem is individual, depending on anything from genetics to the type of exercise involved, and the effects of Reds on the body are varied (see panel). It can go unrecognised by coaches and athletes at all levels.
“People competing at a recreational level often go at it hard,” says Burke. “Maybe running in a marathon is their bucket-list thing to do, so they’ll increase their training and try to lose weight at the same time. They’ve got no support team around them, no access to the sports-specific information that athletes are given and their friends might be telling them they haven’t looked so good in years.”
The latest science suggests cutting down on carbohydrates may be a particular problem as it leads to changes that may weaken bones faster.
“What’s terrible as a practitioner is when you’re dealing with a 30-year-old athlete who has the bones of a 90-year-old and it was preventable,” says Burke. “So, it’s really important that we intervene earlier.”
Reds does seem to be more common in those sports where a lean physique is encouraged, such as gymnastics, cycling and distance running, and in those in which athletes must meet weight-class restrictions.
“In some sports, your body is more on show,” says Burke. “Imagine you’re a swimmer on a starting block wearing a skimpy costume, and people on social media could be commenting on what you look like. If an athlete is young and a perfectionist, you can see how all those factors together can be a disaster.”
She advises anyone taking on a new sport or increasing the amount of exercise they do to get expert help and make sure their diet will be able to support it.
“Sometimes, people are happy to buy a $400 pair of shoes and pay for a gym membership when a consultation with a dietitian could be one of the better investments,” she says. “I’d probably value that over expensive shoes if I was training to run a marathon.”
Flat out
Relative energy deficiency in sport can have wide-ranging effects:
- Hormonal disturbances, loss of periods, erectile dysfunction, low libido
- Weakened bones, susceptibility to stress fractures
- Abdominal pain, cramps, bloating
- Impaired energy metabolism
- Low iron, insufficient red blood cell oxygen-carrying capacity
- Urinary incontinence
- Impaired glucose and blood lipid metabolism
- Depression, exercise dependence/addiction, eating disorders
- Impaired cognitive skills, such as memory, decision-making, spatial awareness
- Sleep disturbances
- Heart rhythm and blood flow abnormalities
- Reduced muscle function
- Reduced growth and development
- Impaired immunity
