Fueling & iron for women in HYROX: the two silent performance killers

Training harder but getting slower? Constantly tired, ill, or injured? For many women in HYROX the problem isn't the training plan. It's one of two things that rarely show up until they've already cost months.

1. Not eating enough for your training (REDs)

The International Olympic Committee's 2023 consensus describes Relative Energy Deficiency in Sport (REDs): when you don't eat enough to cover both training and normal body functions, the body starts cutting back. It affects hormones, bone, immunity, mood and performance (Mountjoy et al., 2023). It's often accidental: HYROX training burns a lot, and "eating clean" or trying to lean out can leave a large gap without you noticing.

Warning signs: missing or irregular periods, bone stress injuries, frequent illness, persistent fatigue, poor sleep, low mood, and performance going backwards despite training.

What helps: eat around training, with a carbohydrate-containing meal or snack before and protein plus carbs after. Don't run long days on a big deficit. Spread protein across the day (about 1.6 g per kg of body weight is a well-supported target for strength gains; Morton et al., 2018).

2. Running low on iron

An estimated 15–35% of female endurance athletes are iron deficient, versus around 5% of the general population (Pedlar et al., 2018). Iron is needed to carry oxygen, so low stores drag down your engine before full anaemia appears. Periods, sweat, foot-strike and lower meat intake all add up.

Warning signs: unusual fatigue, breathlessness on easy runs, poor recovery, feeling cold, and heart rate drifting up at the same pace.

What helps: ask your doctor for ferritin and haemoglobin once or twice a year, more often if you're vegetarian, have heavy periods or are increasing training volume. Eat iron-rich foods with vitamin C, and keep tea and coffee away from iron-rich meals. If you need a supplement, take it with medical guidance. Don't self-dose "just in case."

The bottom line

Fueling isn't a separate topic from training. It's what lets the training work. If two or more of the warning signs above sound familiar, talk to a sports doctor or sports dietitian before adding more training.

General education, not medical advice. If something hurts, leaks, or stops (like your period), see a qualified clinician.

Racing mixed doubles? Women are the scarce side of the mixed pool on Find HYROX Partner — men are already waiting at most races, so women usually match fastest. Find a mixed doubles partner (free) →

Frequently asked questions

References

1. Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med. 2023;57(17):1073–1097.
2. Pedlar CR, Brugnara C, Bruinvels G, Burden R. Iron balance and iron supplementation for the female athlete: a practical approach. Eur J Sport Sci. 2018;18(2):295–305.
3. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376–384.

Keep reading

• Mixed doubles uses men's weights: a woman's race plan
• Should you train around your cycle? What the research says
• Strength training for women in HYROX
• Best HYROX gear for women: bras, shoes, grip
• All HYROX for Women guides