Short answer
A BMI of 14 is considered critically low weight in adults and requires immediate medical attention. It is one of the clearest signs of a severe eating disorder or another serious underlying illness. In children, the interpretation depends on age — for a very young child (2–3 years), the raw value may fall within the normal range, but in school-aged children and adolescents, a BMI of 14 is always a sign of severe underweight that must be investigated.
Seek medical attention if BMI is 14
If you, a child, or someone close to you has a BMI of 14 — contact healthcare services without delay. A vårdcentral (primary health centre), emergency department, or 1177 can provide guidance. If an eating disorder is suspected, there are specialised eating disorder units in all regions; children and adolescents can be assessed via BUP (child and adolescent mental health services) or a paediatric clinic.
BMI 14 in adults
Fixed BMI thresholds are used for adults:
| BMI | Classification |
|---|---|
| Under 15 | Very severe / critical underweight |
| 15–16 | Severe underweight |
| 16–17 | Moderate underweight |
| 17–18.5 | Mild underweight |
| 18.5–25 | Normal weight |
A BMI of 14 in adults is critically low. Risks include:
- Severe malnutrition and electrolyte disturbances
- Cardiac arrhythmias and sudden cardiac death
- Osteoporosis and fractures
- Hormonal disturbances (absent periods, infertility)
- Weakened immune system
- Cognitive and psychological impairment
In severe anorexia, inpatient admission may be necessary to restore nutrition safely (refeeding must be managed in a controlled manner to avoid refeeding syndrome).
BMI 14 in children
In children, BMI must always be interpreted against age and sex using iso-BMI (Cole 2000). The raw value of 14 means different things at different ages:
| Age | BMI 14 corresponds approximately to |
|---|---|
| 2–3 years | Mild underweight (normal 14–17.5) |
| 5 years | Mild underweight |
| 7 years | Moderate underweight |
| 10 years | Severe underweight |
| 12 years | Severe underweight |
| 15 years | Very severe / critical underweight |
Calculate the iso-BMI for your child using our iso-BMI calculator.
When must you seek help?
Contact healthcare services without delay if the child has a BMI of 14 or if any of the following apply:
- Rapid weight loss over weeks or months.
- Restrictive eating, skipping meals, rituals around food.
- Binge eating followed by vomiting or excessive exercise.
- Altered body image, expressing that they are "too fat".
- Fatigue, feeling cold, dizziness, palpitations.
- Absent or delayed puberty, missed menstrual periods.
For children and adolescents, BUP (child and adolescent mental health services), a paediatric clinic, or a specialised eating disorder unit is the appropriate service. In acute situations: attend an emergency department.
Related BMI values
- BMI 15 — severe underweight in adults.
- BMI for children — calculator and interpretation.
- Iso-BMI for children.
Related questions
- What does BMI 15 mean?BMI 15 is severe underweight in adults — for children, the interpretation depends on age.
- How much should an 11-year-old weigh?There is no single correct weight for an 11-year-old — how iso-BMI works at 11 years of age.
- What is a normal weight for a 12-year-old?Puberty, height and sex all play a part — this is how a 12-year-old's weight is assessed.
Sources
- WHO — BMI classification
- Cole TJ et al. — Establishing a standard definition for child overweight and obesity (BMJ 2000)
- 1177 Vårdguiden — Eating disorders
Last updated: June 2026