Female runner, lost my period, finally admitted I'm undereating — how to rebuild safely?
29F. Running 40-50 miles per week training for a fall marathon. My period disappeared around January and I spent 5 months convincing myself it was "just stress" or "just training."
Last week my RD actually said the words RED-S to me and I cried in her office. I've been in denial. I've been undereating and I know it. I've been afraid of gaining weight as a runner so I just kept eating less as training volume went up, which is the exact opposite of what the physiology requires.
I don't know how to rebuild. I'm terrified of gaining a bunch of weight. I'm terrified of losing my fitness. I know those are both stupid things to be terrified of compared to the actual health consequences. But my brain is where it is.
How did others rebuild? How long until my period came back? Did you lose fitness? Did you gain a lot of weight or just normalize?
RED-S survivor and a running-specific RD here — so I have both sides of this. First: you are so, so not alone. Amenorrhea in endurance female athletes is one of the most under-diagnosed conditions in sports medicine. You did the hardest thing by naming it.
Rebuild protocol that actually works (with your RD, not instead of her):
- Full rest or very low volume for the first 4-6 weeks. Yes, really. The energy deficit has to close before the hormonal signal returns.
- Add 400-600 calories/day to maintenance. Prioritize carbs (endurance athletes need them and RED-S recovery is carb-positive, not carb-phobic).
- Lift 2-3x/week. Non-negotiable. Muscle mass helps bone density which is what you're really protecting here.
- Period typically returns 3-9 months after energy balance is restored. Wide variance. Some it's faster. Mine was 7 months.
Been there. Amenorrhea for 18 months, rebuilt over a year, period came back, ran my PR six months after that. Here's the honest truth nobody told me: you will gain weight during the rebuild. I gained 8 lbs. Felt awful about it mentally for 4 months. Then my running got BETTER. Then I set a PR. Then I realized the 8 lbs was fuel and muscle, not "weight."
The book "Roar" by Stacy Sims is required reading for women in endurance sports. I wish every female runner read it at 18. She's the loudest voice on female physiology being different from male physiology and on why undereating is so specifically dangerous for female athletes.
Not a runner but was underweight and amenorrheic for 2 years in my 20s. The mental part is harder than the physical part. The physical part is "eat more." The mental part is "believe that gaining weight isn't a failure." Therapist helped me more than any RD on the mental side.
Bone density scan if you haven't had one. Amenorrhea + endurance training is a really efficient way to reduce bone mineral density. If you're low, there are interventions (calcium, D, weight-bearing work) but you need the data to know where you stand. This is NOT optional for 5+ months of amenorrhea.
Thank you all. I've been lurking on this forum for years and the amount of gentleness here is something else. Booking the DEXA this week. Ordered Roar. Already talked to my RD about the 4-6 weeks low-volume thing and she's 100% on board, I just needed to hear it from people who'd lived it. I'll update in a few months.
One thing that helped me mentally during rebuild: started tracking running CAPABILITY instead of weight. How far could I run at Zone 2 before HR drifted? What was my 5K pace at controlled effort? Those numbers went UP as I ate more. Made the weight gain feel like fuel, not failure.
Male runner chiming in — the female physiology piece is real and I won't pretend to know it. But on the general "rebuild from undereating" thing: expect your resting HR to come DOWN (counterintuitive but true; it's a sign the body is no longer fighting to function). Watch for it. It's one of the first good signs.
Adding one more thing for @runnerEmma and anyone else reading this later: do NOT set a weight goal for the rebuild. Do not. Your body will find its settling point and it's almost certainly 5-12 lbs higher than your amenorrheic weight. That weight IS your healthy weight. The lower number was the unhealthy one.
3-month update: DEXA came back osteopenic (not osteoporotic — caught it in time). Period returned 11 weeks after I started the rebuild protocol. Gained 9 lbs. Hate it and don't hate it. Running is easier. Sleeping better. Haven't been injured once in 12 weeks, first time in 2 years. Thank you, all of you. This thread saved me.