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ENERGY AVAILABILITY CALCULATOR

Are you eating enough to support your training? Check your EA score and RED-S risk.

Average across the week. Estimate is fine.

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Quick answer

Enter training hours, daily calorie intake, body weight, and gender. The calculator returns energy availability in kcal per kg of fat-free mass and screens you against RED-S risk thresholds (under 30, 30-45, and over 45 kcal/kg FFM/day).

WHAT IT DOES

Energy availability is the calories left over for everyday physiological function once you've subtracted what training burned. Chronic low energy availability is the root cause of RED-S — Relative Energy Deficiency in Sport — which costs cyclists power, immune function, sleep, hormonal health, and bone density. This tool tells you whether you're under-fuelling without realising.

WHO IT'S FOR

  • →Riders pursuing race weight
  • →High-volume cyclists training 12+ hours per week
  • →Anyone with persistent fatigue, frequent illness, or stalled progress
  • →Female cyclists with menstrual irregularity or stress fractures
  • →Coaches screening athletes

HOW IT WORKS

Energy Availability (EA) = (Daily intake kcal − Exercise energy expenditure kcal) ÷ Fat-free mass (kg). Three thresholds matter: above 45 kcal/kg FFM/day = optimal; 30-45 = sub-optimal but not severely impaired; below 30 = clinical low energy availability with measurable hormonal and performance consequences.

  1. 01

    Track intake honestly for 7 days

    Use a food-tracking app and weigh portions. Most amateurs under-report by 20-30%. Use the 7-day average rather than a single day.

  2. 02

    Estimate exercise energy expenditure

    Cycling watts × hours × 3.6 ≈ kcal. A 75kg rider doing 10 hours/week at 180W average burns roughly 6,500 kcal/week (≈930/day).

  3. 03

    Estimate fat-free mass

    Body weight × (1 − body fat fraction). Use a DXA, bioimpedance scale, or skinfolds. A 75kg rider at 15% body fat has ~64 kg fat-free mass.

  4. 04

    Read the result

    If EA is under 30 kcal/kg FFM/day, raise food intake or reduce training load — ideally both. If 30-45, you're under-fuelling enough to limit adaptation. Above 45 is the target zone.

EXAMPLE CALCULATIONS

Female 60kg rider, 12hr/week training

  • · Intake: 2,400 kcal/day
  • · Training: 12 hr/week at 150W
  • · Weight: 60kg
  • · Body fat: 22%

EA: ~28 kcal/kg FFM/day — clinical low EA. Add 300-400 kcal/day to lift above the 30 threshold.

Male 75kg rider, 8hr/week training

  • · Intake: 3,200 kcal/day
  • · Training: 8 hr/week at 200W
  • · Weight: 75kg
  • · Body fat: 15%

EA: ~46 kcal/kg FFM/day — optimal. Maintain intake around hard training blocks.

LIMITATIONS

EA estimates depend on accurate calorie tracking and accurate exercise expenditure — both have meaningful error bars. The thresholds (30 / 45 kcal/kg FFM/day) come from research mostly on female athletes; male data is more sparse. EA is a screening tool, not a diagnosis. RED-S diagnosis requires medical input and looks at symptoms (low resting HR, missing periods, recurrent illness, stress fractures) alongside the number.

When to see a coach

If your EA is below 30, you've had recurrent illness, stress fractures, missing periods, or your power is dropping despite training — stop adjusting calories alone and book in with a sports physician and a registered dietitian. RED-S is a medical issue, not a coaching one.

FREQUENTLY ASKED QUESTIONS

What is RED-S in cycling?+

RED-S — Relative Energy Deficiency in Sport — is a syndrome caused by chronically low energy availability. Symptoms include drops in performance, recurrent illness, low libido, missing periods (in females), low testosterone (in males), bone stress injuries, low resting HR, sleep disruption, and irritability. Cyclists are at high risk because the sport is body-weight sensitive.

What is a healthy energy availability for cyclists?+

Above 45 kcal per kg of fat-free mass per day is considered optimal. 30-45 is sub-optimal and limits training adaptation. Below 30 is clinical low energy availability with measurable hormonal and performance consequences and shouldn't be sustained beyond short, supervised body-comp phases.

How is energy availability different from calorie deficit?+

A calorie deficit is intake minus total energy expenditure (BMR + activity). Energy availability is intake minus exercise expenditure, divided by fat-free mass — what's left over to fuel basic physiological function. You can be in a small calorie deficit AND in healthy EA, or in calorie balance and dangerously low EA if training volume is high. EA is the more useful number for athletes.

Can I diet for race weight without low energy availability?+

Yes — but only if the deficit is small (≤300-400 kcal/day), the duration is limited (4-12 weeks), protein is high (1.6-2.2 g/kg), and you fuel hard training days fully. The danger is dieting through a high-volume training block with under-fuelled key sessions — that's the recipe for RED-S.

How do I know if I have RED-S?+

EA below 30 for an extended period plus symptoms — drops in power, recurrent illness, missing periods, stress fractures, low resting HR, poor sleep, low libido. Diagnosis requires medical input, blood work, and DXA. Don't self-diagnose; do screen yourself with this calculator and book in if multiple flags are present.

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