Undereating and low energy availability
Not getting enough food for your needs can affect health and daily functioning, whether intentional or not. Symptoms deserve assessment rather than assumptions about fitness or body size.
In short
Understanding undereating and low energy availability
Low energy availability means that too little dietary energy remains for normal body functions after activity demands. In sport, relative energy deficiency in sport (REDs) describes possible health and performance consequences of problematic low energy availability.
It can affect different genders and occur without obvious weight change. Fatigue, injuries and menstrual changes have many possible causes, so a clinician must assess the situation rather than diagnose it from a symptom list.
Does this sound familiar?
This might sound like your situation
These experiences are reasons to seek support, not a checklist for diagnosing yourself.
- You are persistently tired, cold or struggling to recover
- Injuries or illness keep recurring
- Periods have changed or stopped
- You find it difficult to eat enough around a demanding schedule
SmartEating recommends
What makes the biggest difference?
These describe supportive directions and professional care, not instructions for treating yourself.
Assess the whole situation
Discuss food intake, training, symptoms and other health concerns with a clinician experienced in sport and nutrition.
Do not normalise missed periods
Menstrual changes warrant assessment and can have several causes. They are not an inevitable sign of being fit.
Plan changes professionally
Nutrition and activity adjustments should reflect physical risk and individual needs. This is not an online training or feeding prescription.
Explore why intake is low
Time pressure, appetite, food access and distress around eating may all be relevant. An eating disorder may require additional care.
Information, not treatment
Persistent fatigue, recurrent injuries or menstrual changes need medical assessment. These symptoms are not specific to low energy availability. Severe weakness, fainting or chest symptoms require urgent care.
- Seek urgent care for fainting, chest pain, severe weakness, confusion or other acute symptoms.
- Use your local emergency service for immediate danger to life or safety, including risk of self-harm.
- Children and teenagers can ask a trusted adult or child-health professional for help accessing care.
This page does not provide a diagnosis, calorie targets, weight goals, BMI thresholds or a treatment plan. UK and US sources are labelled; local service availability varies.
Common questions
What people ask us most often.
Can this happen without obvious weight loss?
Yes. Body size or weight change alone cannot establish adequate intake or rule out an eating-related health problem. Individual assessment is needed.
Are missed periods normal with training?
Menstrual changes should be assessed rather than assumed to be a normal training adaptation. Low intake can be one explanation, but other causes need consideration.
Can different genders be affected?
Yes. Inadequate intake can affect people of different genders, although the signs are not identical for everyone. Assessment should not rely on menstruation alone.
Should I stop exercising?
The safe level of activity depends on your health. Ask a clinician; they may recommend changes or a pause. Feeling able to exercise does not establish that it is safe.
How long does recovery take?
There is no reliable timeline from a webpage. Causes, duration and physical complications differ, and recovery should be monitored individually.
Who can help?
A local doctor or sports-medicine clinician can assess symptoms, with a dietitian and eating-disorder care involved where appropriate. Recurrent injury or marked fatigue should not be managed by meal ideas alone.
Personal nutrition
Support should fit the person, not a label
Physical risk, psychological distress and everyday circumstances need individual assessment. Neither appearance nor a website can determine the care required.
For concerns about eating disorders, our start link opens the dedicated support pathway, not automatic independent meal planning. Clinical availability is checked separately and a contact request does not establish treatment.
- You do not need to diagnose yourself
- A doctor can assess physical safety
- Practical support should fit an agreed care plan
A clinical dietitian may contribute as part of an appropriate care team.
General meal-planning tools do not treat eating disorders or manage refeeding risk. Discuss any practical tool with your treating team before using it in recovery.
Seek local healthcare advice
A doctor can assess physical health and help you find appropriate care.
Use the dedicated support pathway
Our website offers information and a country-specific support or contact option, not a self-directed treatment plan.
Clarify appropriate care
Professional qualifications, service availability and any clinical follow-up must be assessed separately.
Ready to get help with undereating and low energy availability?
Explore the dedicated support pathway. Clinical availability and appropriate care must be assessed separately.
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