Global Running Day: How to Avoid Low Energy Availability in Running
Global Running Day is a reminder of how rapidly running continues to grow as one of the most widely participated endurance sports in the world.
While exact global participation is difficult to measure precisely, large-scale sport and public health datasets consistently show that:
- Hundreds of millions of people run or jog recreationally worldwide
- Running is consistently ranked among the top 3–5 most participated sports globally
- Major participation datasets estimate tens of millions of annual race finishers globally when combining 5K, 10K, half-marathon, and marathon distances
- More than 29 million marathon and half-marathon finishers in the United States alone (2010–2023) have been recorded in race registries
- Global participation in organised running events has continued to increase alongside the growth of digital tracking platforms and recreational running communities
Running is accessible, social, and deeply embedded in modern fitness culture.
But alongside this growth is a persistent issue in endurance sport:
Many runners are unknowingly under-fuelling.
The hidden issue: low energy availability
Running performance is not determined solely by training volume or fitness.
It depends on whether the body has sufficient energy available to support both exercise and essential physiological function.
When energy intake is chronically lower than energy expenditure, this leads to low energy availability, which underpins:
Relative Energy Deficiency in Sport
This is especially relevant in long-distance running, where energy demands are high and appetite is often suppressed.
What the research shows
Low energy availability is widely documented in endurance sport:
- 22% to 58% of endurance athletes show signs of low energy availability risk depending on sport and measurement method
- In male endurance athletes, ~47% were identified as at risk of low energy availability in screening research settings (Ackerman et al., 2019 framework applications)
- Ultra-endurance reviews report that up to 65% of athletes may show risk markers in some cohorts, depending on methodology
Key peer-reviewed consensus papers:
- Mountjoy et al., IOC RED-S Consensus Statement (British Journal of Sports Medicine, 2018/2023 updates)
- Ackerman et al., 2019 RED-S screening and prevalence research (BJSM)
- Melin et al., 2019 energy availability framework (International Journal of Sport Nutrition and Exercise Metabolism)
- Burke & Deakin sports nutrition consensus work on endurance carbohydrate needs
Across the literature, one message is consistent:
Under-fuelling in endurance athletes is common, often unintentional, and frequently under-recognised.
Why runners are particularly at risk
Long-distance runners face a unique combination of factors:
- High weekly training volume
- Repeated glycogen depletion
- Appetite suppression after prolonged exercise
- Intentional restriction for body composition goals
- “Clean eating” or low carbohydrate dietary patterns
- Under-recovery between sessions
Over time, these factors can create chronic low energy availability without the athlete realising it.
Why this matters
Low energy availability affects multiple physiological systems:
- Hormonal function (including reproductive hormones)
- Bone mineral density and stress fracture risk
- Immune function and illness susceptibility
- Metabolic rate and energy regulation
- Recovery and training adaptation
Importantly, athletes may still appear lean, fit, and high-performing while internal physiological strain is developing.
How to avoid low energy availability in running
1. Fuel before long runs
For sessions:
- Carbohydrate-rich snack 30–90 minutes before
- Larger meal 2–4 hours before longer runs
Purpose:
- Maintain glycogen availability
- Reduce physiological stress response
- Improve endurance and pacing stability
2. Fuel during long runs
For endurance sessions:
- 30–60g carbohydrate per hour
- Up to 90g per hour in trained athletes with gut adaptation
Evidence from sports nutrition research consistently shows performance benefits of carbohydrate intake during endurance exercise (Jeukendrup, sports nutrition literature).
Purpose:
- Maintain blood glucose
- Delay fatigue
- Spare muscle glycogen
- Sustain performance output
3. Recover after running
Within 1–2 hours post-run:
- Carbohydrates to replenish glycogen
- Protein to support muscle repair
- Fluids and sodium to restore hydration
Purpose:
- Restore energy availability
- Support adaptation
- Reduce cumulative fatigue
4. Do not rely on hunger alone
In endurance sport, appetite is often suppressed after training.
This means:
Hunger is not a reliable indicator of energy requirements.
Structured fuelling is often necessary, especially during high training loads.
Bio-individuality and RED-S
One of the biggest misconceptions in nutrition is that there is a single correct way for everyone to eat.
In reality, no two bodies are the same.
Each athlete has different:
- Genetics
- Hormonal profiles
- Gut microbiome composition
- Training load
- Stress levels
- Sleep quality
- Recovery capacity
- Energy expenditure
This is known as bio-individuality.
It is also why RED-S can present so differently between individuals.
Some athletes lose weight, others do not.
Some lose menstrual function, others do not.
Some experience obvious symptoms, while others continue performing while internal physiological disruption develops silently.
Because of this variability, there is no universal calorie target or fixed meal plan that ensures protection from low energy availability.
What matters is whether the body has sufficient energy to support both exercise and essential physiological processes.
Energy is not just for training
Even on rest days, the body requires energy for:
- Brain function
- Heart and lung function
- Hormone production
- Immune activity
- Digestion
- Cellular repair
Exercise is only one component of total daily energy demand.
This is why chronic restriction, even on non-training days, can contribute to long-term under-fuelling.
Recovery is not one-size-fits-all
When athletes first learn about RED-S, one of the most common questions is:
“Do I need to gain weight?”
The answer is:
Maybe. Maybe not.
Recovery is not defined by weight change.
It is defined by restoring energy availability.
Some athletes require weight restoration, while others recover through increased energy intake without significant weight change.
Common clinical guidance includes gradual increases in energy intake, often around 300–600 kcal/day depending on individual needs, alongside adequate carbohydrate, protein, and fat intake.
Carbohydrates are especially important due to their role in glycogen restoration, training adaptation, and hormonal signalling.
Introducing RED-SCUE Energy Bars
RED-SCUE Energy Bars are designed to support athletes and exercisers who need practical, digestible carbohydrate fuel.
Formulated with:
- Cassava-based carbohydrates
- Plantain (fufu) energy sources
- Natural vitamins, minerals, and carb-first, plant-root energy
They provide:
- Rapid carbohydrate availability
- Easy digestion during exercise
- Whole-food-based endurance fuel
- Reduced gastrointestinal strain compared to some ultra-processed alternatives
They can be used:
- Everyday energy support
- Before runs
- During sessions
- After training for recovery support
Key takeaway
Running performance is not just about how much you train.
It is about whether your body has enough energy to adapt to that training.
When energy availability is too low:
- Recovery slows
- Injury risk increases
- Performance plateaus
- Hormonal and metabolic function are impaired
Final message
Avoiding low energy availability is not about perfection.
It is about consistency.
It is about matching fuel to demand.
And it is about recognising that energy is required every single day—not just on training days.
RED-SCUE Energy Bars are designed to support that consistency with accessible, gut-friendly carbohydrate fuel for endurance athletes.
