Energy Availability and RED-S: Warning Signs for Lifters

Published October 23, 2026 · Last reviewed October 23, 2026

What the sources say

• Energy availability. The ACSM position stand defines it as dietary energy intake minus exercise energy expenditure. The same stand says low energy availability appears to be the factor that impairs reproductive and skeletal health, that it may be inadvertent, intentional or part of an eating disorder, and that most effects appear below 30 kcal per kg of fat-free mass per day. That figure is a research observation, not a personal target or a diagnosis.
• RED-S (REDs). The IOC’s 2023 consensus defines it as a syndrome of impaired physiological and/or psychological functioning in female and male athletes caused by exposure to problematic (prolonged and/or severe) low energy availability. Outcomes include decreases in energy metabolism, reproductive function, musculoskeletal health, immunity, glycogen synthesis, and cardiovascular and haematological health, leading to impaired well-being, increased injury risk and decreased performance.
• A spectrum, not a switch. The 2023 statement describes low energy availability as adaptable or problematic depending on individual factors, and adds a role for low carbohydrate availability and mental health. It introduces a clinical assessment tool that rates severity and risk and gives training and competition recommendations. Those decisions belong to a clinician.
• Not only elite sport. The IOC editorial says the problem occurs across all sports and levels of participation. How often it affects recreational lifters is not reported in the sources here.
• It looks like overtraining. A 2021 review found the symptoms of training overload and RED-S overlap heavily, and that 18 of 21 overload studies that measured intake showed a drop in energy or carbohydrate availability. The joint ECSS and ACSM consensus lists dietary caloric restriction and insufficient carbohydrate or protein among causes to exclude before an overtraining diagnosis.
• The Triad. The 2007 ACSM stand and the 2014 coalition consensus describe three linked components: low energy availability with or without disordered eating, menstrual dysfunction and low bone mineral density. The 2014 statement gives physicians a risk-stratification system for sport clearance and return to play.
• Treatment direction. The ACSM stand says the first aim of treatment is to raise energy availability by increasing intake and/or reducing exercise energy expenditure, and recommends a team that includes a physician or other health-care professional, a registered dietitian and, where there is an eating disorder, a mental health practitioner.

Durable Strength Practice (not new): when progress stalls, check fuelling and recovery before adding sets. Adding volume to an energy deficit is the wrong direction.

A fuelling and recovery check-in

Site heuristic, not a study finding The four-week window and the two-week hold are the site’s cautious design. The signs to raise come from the consensus outcomes above. This is a prompt to talk to a clinician and does not diagnose anything.

1. Write down the last four weeks: training days, session length and any planned cut in food intake.
2. Note changes in periods (missed, absent or newly irregular), illness, injuries, mood and sleep.
3. Check whether strength or session quality has fallen even though you trained consistently.
4. If your periods have stopped or become irregular, or worry about food or body shape is shaping your training, book a clinician visit now.
5. If you only have fatigue or flat progress, hold volume steady for two weeks without adding sets, then review the log.
6. Take the written timeline to the appointment.

Decisions by situation

Condition: Fatigue and flat progress while eating less or training more

Impact: Training overload and low energy availability look alike, and the ECSS and ACSM consensus says other causes, including dietary restriction, have to be excluded.

Action

For B, C Hold volume steady for two weeks, do not add sets, and review the log. If ratings stay low, book a clinician visit.

Why it helps

The 2021 review found the symptom overlap significant and found signs of reduced energy or carbohydrate availability in most overload studies it analysed.

Verification

Your log shows two weeks of unchanged volume, and the ratings either recover or you have an appointment.

For A Early, steady progress is normal. If a new lifter loses energy and strength across a few weeks, use the readiness check first.

Source: Stellingwerff et al. 2021 review; Meeusen et al. consensus.

Condition: Periods have stopped, become irregular, or bone-related injuries repeat

Impact: Menstrual dysfunction and low bone mineral density are two of the three Triad components, and bone health is among the REDs outcomes.

Action

See a clinician promptly and bring the written four-week timeline. Do not add training volume or restrict food further while you wait.

Why it helps

The ACSM stand says early intervention matters and that treatment starts with raising energy availability, under a clinician-led team.

Verification

An appointment is booked and the timeline names the date the change began.

For E A clinician decides clearance and return to training. The 2014 consensus gives physicians categories for it. See the returning-to-lifting guide.

Source: ACSM position stand on the female athlete triad; 2014 triad consensus; IOC 2023 statement.

Condition: You coach lifters and notice a pattern in one of them

Impact: The IOC editorial calls for a ‘health-first, performance-second’ culture and warns against pressure toward unhealthy body-composition goals.

Action

For D Do not weigh or comment on body shape. Describe what you observed (missed sessions, a drop in strength, injuries, illness), say you are concerned for her health, and refer her to a clinician.

Why it helps

The ACSM stand says education of athletes, coaches and trainers is a priority, and the IOC editorial says coaches have a role in prevention.

Verification

She has a referral and you have written down what you saw and when, without diagnostic language.

A coach’s role is to notice, listen and refer. See coaching cues and language.

Source: IOC REDs editorial; ACSM position stand.

How it works

Energy availability is the food energy left for the body’s other work once training has been paid for. When it stays low, the body trims spending on functions such as reproduction, bone remodelling and immunity, which is why the outcomes in the consensus read like a list of unrelated problems. The 2023 statement frames it as a range from adaptable to problematic, which is why a clinician assesses severity and risk and not a single number.

Your part is to notice early and to avoid the reflex of adding training. The deloads and plateaus guide covers a lighter week, and the cycle guide shows how to log changes in your periods.

Worked example

A hypothetical calculation that only illustrates the ACSM definition. Say a lifter eats 2,000 kcal a day, her sessions use about 500 kcal, and her fat-free mass is 45 kg. Energy availability = (2,000 − 500) ÷ 45 = 33.3 kcal per kg of fat-free mass per day.

If she raises her training so sessions use 700 kcal and eats the same, the result is (2,000 − 700) ÷ 45 = 28.9, which falls under the 30 kcal mark the ACSM stand mentions. The point is how quickly the figure moves, not that you should calculate your own: intake, exercise energy and fat-free mass are hard to measure at home, and the 30 kcal mark is a research observation. A clinician or registered dietitian can assess it properly.