Female Cyclist With Low Energy Availability and Amenorrhea
A 24-year-old female road cyclist (58 kg, 170 cm, fat-free mass 46 kg) trains 18 hours per week and wants to lose 3 kg before a climbing camp. Her BMI is 20.1. Her 24-hour recall shows about 1,800 kcal/day and 850 kcal/day of training energy expenditure. She reports 6 months of amenorrhea, a recent metatarsal stress fracture, ferritin 18 ng/mL, fatigue, and low libido. She believes lighter is faster and has started skipping breakfast and weighing food. She has no diagnosed eating disorder, but she reports guilt when she misses a session and avoids social meals. Her coach wants weekly weigh-ins and a 1,400-kcal meal plan. She asks whether a ketogenic diet will help her climb faster while keeping muscle. You are asked to review her case and advise the athlete and coach.
1. Calculate her estimated energy availability and interpret it. What are the limitations of this calculation?
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EA = (intake − exercise energy expenditure) / fat-free mass = (1,800 − 850) / 46 = 20.7 kcal/kg FFM/day. This is below the commonly used 30 kcal/kg FFM/day threshold for low energy availability and fits a high-risk picture with amenorrhea, stress fracture, low ferritin, and fatigue. It is not a diagnosis of RED-S; it is a screening calculation that needs clinical confirmation. The estimate is limited by recall error, changing daily training, and use of an estimated FFM. I would not present it as precise but as evidence that her current fueling is inadequate.
2. Evaluate her goal to lose 3 kg and propose priorities for the next 8–12 weeks. Include approximate intake and nutrient targets.
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Her goal to lose 3 kg should be paused. To reach EA of at least 30 kcal/kg FFM, net energy would need to be 30 × 46 = 1,380 kcal/day; with 850 kcal exercise, intake would need to be at least 2,230 kcal/day, about 430 kcal/day more than now, and likely more to restore menstrual and bone health. Priorities are increasing carbohydrate around training, protein to about 1.6 g/kg (about 93 g/day), calcium 1,000–1,200 mg/day, vitamin D, and iron-rich foods with vitamin C; refer for ferritin evaluation. Reduce or modify training and involve a physician and registered dietitian. Weight loss can be reconsidered only after health and energy status are restored.
3. The coach insists on weekly weigh-ins and a 1,400-kcal target. How do you respond within your scope and ethics?
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I would not agree to coach-led weigh-ins or a 1,400-kcal target. That would deepen the energy deficit and could worsen bone, menstrual, and psychological health. My role is to explain the risk in plain language, keep the athlete's confidentiality, document the conversation, and recommend a joint plan with a physician and registered dietitian. I can support meal timing, grocery strategies, and training fuel, but I should not diagnose RED-S, prescribe a therapeutic diet, or clear her to compete. If the coach persists, escalate through appropriate safeguarding and medical channels.