Under-fuelling and missed periods: understanding RED-S in active women

Today’s guest post feature is on behalf of Jane McClenaghan, a leading nutritionist in Northern Ireland, on how under-fuelling could lead to RED-S (Relative Energy Deficiency in Sport) and cause missed periods in women.

When your body stops listening: what happens when you miss your period

There are lots of reasons your period might stop suddenly. And it’s not always pregnancy. When your period stops for three months or more, doctors call it amenorrhoea. It sounds clinical, but it’s your body’s way of saying, “I need a break.”

Common reasons for missing periods

One of the most common reasons for missing periods is RED-S – short for Relative Energy Deficiency in Sport. It happens when you don’t eat enough to fuel the energy you’re burning through exercise. In plain English? You’re under-eating and over-exercising.

And before you think it only happens to elite athletes, it doesn’t. RED-S can affect anyone, from the weekend runner to a midlife woman like me who loves combat classes, but very occasionally forgets to eat enough to match her effort.

RED-S affects more than your cycle

RED-S doesn’t stop at your hormones. It can affect almost every system in your body, your immune system, heart, bones, and even your brain. When you’re running on empty, your body simply can’t keep up with what you’re asking it to do.

Under-fuelling leaves you weaker, more fatigued, slower to recover, and more injury-prone. And while a strong coffee might help you power through the morning, it’s no substitute for proper nutrition.

How to fuel your body for training

If you’ve upped your exercise, your nutrition needs to keep pace. Think of your body as a car, you can’t expect peak performance if the tank’s running on fumes. Here’s how to get it right:

Eat enough and consistently

When you move more, you need to eat more. Don’t fear food, it’s fuel. If your workouts have intensified, increase your portion sizes slightly or add a couple of healthy snacks during the day to balance your energy output.

Balance your plate

Your body needs the big three macronutrients for fuel, energy and recovery:

• Protein for muscle repair and hormone balance, aim for a palm-sized portion of chicken, fish, tofu, Greek yoghurt, nuts, seeds or pulses at each meal.
• Carbohydrates for energy and recovery, choose fibre-rich options like oats, brown rice, wholemeal pasta or wholegrain bread.
• Healthy fats for hormone balance, brain health and reduced inflammation, include avocado, olive oil, flaxseed, oily fish or nut butters daily.

  

Never train on an empty stomach

Training fasted might sound “disciplined,” but it’s counterproductive. You’ll perform worse, recover slower, and increase your risk of injury. Even something light like a banana and yoghurt will help you train smarter.

Eat for recovery

Your post-workout meal is as important as the workout itself. Aim to eat within an hour of finishing, ideally a mix of protein, carbs and fats. Jane suggests overnight oats with Greek yoghurt, berries and Linwoods flaxseed, topped with nuts and coQ10 for sustained energy and muscle repair.

About Jane McClenaghan

Jane McClenaghan is Northern Ireland’s most recognised nutritionist with over 20 years’ experience. Her company, Vital Nutrition, specialises in health and wellbeing programmes for corporate and community clients, as well as one-to-one consultations. Jane writes a weekly column for the Irish News, appears regularly on BBC Radio and U105, and contributes to The Belfast Telegraph. She’s also the author of two bestselling books on nutrition.