Anorexic BMI Calculator - Assess Underweight Severity

Free BMI calculator to assess underweight severity and eating disorder risk with WHO classifications and professional guidance

Updated: November 2025 • Free Tool

Anorexic BMI Calculator

Note: This calculator is for educational purposes. Seek professional help if concerned about eating disorders.

Results

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What is an Anorexic BMI Calculator?

An Anorexic BMI Calculator is a free health assessment tool that calculates body mass index and evaluates underweight severity using WHO classifications for anorexia nervosa. It provides health risk information and professional guidance recommendations, helping identify when medical intervention is needed for eating disorders and severe underweight conditions.

This calculator works for:

  • Health assessment - Evaluate underweight severity
  • Eating disorder awareness - Recognize warning signs
  • Medical guidance - Know when to seek help
  • Recovery tracking - Monitor weight restoration progress

To calculate healthy weight range, check out our Ideal Body Weight Calculator to determine target weight for your height and frame size.

For general BMI assessment, explore our BMI Calculator to understand body mass index across all weight categories from underweight to obese.

To assess if overweight, use our Overweight Calculator to determine excess weight and get personalized weight management recommendations.

For body composition, try our Body Fat Percentage Calculator to assess fat mass and lean body mass distribution.

How Anorexic BMI Calculator Works

The calculation uses standard BMI formula:

BMI = Weight (kg) / Height (m)²

WHO underweight classifications:

  • Severe Underweight = BMI < 16.0 (critical)
  • Moderate Underweight = BMI 16.0-16.99 (serious)
  • Mild Underweight = BMI 17.0-18.49 (concern)
  • Normal Weight = BMI 18.5-24.9 (healthy)

BMI below 17.5 is one diagnostic criterion for anorexia nervosa. However, eating disorder diagnosis requires comprehensive medical and psychological evaluation. BMI alone doesn't diagnose anorexia. Seek professional help for accurate assessment.

Key Concepts Explained

Anorexia Nervosa

Eating disorder characterized by extreme food restriction, intense fear of weight gain, and distorted body image. Requires professional treatment.

Malnutrition

Severe underweight causes nutrient deficiencies, weakened immune system, organ damage, and life-threatening complications without treatment.

Medical Complications

Low BMI causes heart problems, bone loss, infertility, cognitive impairment, and increased mortality risk. Early intervention crucial.

Recovery Process

Treatment includes medical monitoring, nutritional rehabilitation, psychotherapy, and family support. Full recovery is possible with proper care.

How to Use This Calculator

1

Enter Height

Input accurate height in centimeters. Use recent measurement for precise BMI calculation.

2

Enter Weight

Input current weight in kilograms. Use accurate scale measurement.

3

Calculate BMI

Click Calculate to see BMI, classification, severity level, and health recommendations.

4

Seek Help

If BMI indicates severe underweight, contact healthcare provider or eating disorder specialist immediately.

Benefits of Using This Calculator

  • Early Detection: Identify severe underweight and eating disorder risk before life-threatening complications develop.
  • WHO Classifications: Uses internationally recognized underweight severity categories for accurate assessment.
  • Health Risk Awareness: Understand medical complications of low BMI and importance of professional treatment.
  • Professional Guidance: Get recommendations on when to seek medical help and eating disorder treatment.
  • Recovery Monitoring: Track weight restoration progress during eating disorder treatment and recovery.
  • Educational Resource: Learn about healthy weight ranges and eating disorder warning signs for awareness.

Factors That Affect Your Results

1. BMI Limitations

BMI doesn't distinguish muscle from fat or account for body composition. Athletes may have low BMI without health risks. Medical evaluation needed.

2. Age Considerations

BMI interpretation differs for children, adolescents, and elderly. Growth charts used for youth. Elderly may have different healthy ranges.

3. Medical Conditions

Chronic illnesses, medications, and metabolic disorders affect weight. Low BMI doesn't always indicate eating disorder. Comprehensive evaluation required.

4. Psychological Factors

Anorexia diagnosis requires psychological symptoms: fear of weight gain, body image distortion, food restriction. BMI is one criterion among many.

5. Individual Variation

Natural body diversity means healthy weight varies. Some people naturally have lower BMI. Context and overall health matter more than numbers alone.

Anorexic BMI Calculator - Free underweight assessment calculator with instant results
Professional anorexic BMI calculator interface for assessing underweight severity. Features WHO classifications and professional guidance recommendations.

Frequently Asked Questions (FAQ)

Q: What BMI is considered anorexic?

A: BMI below 17.5 is one diagnostic criterion for anorexia nervosa. Severe underweight is BMI below 16, moderate 16-16.99, mild 17-17.49. However, anorexia diagnosis requires psychological evaluation, not just BMI. Seek professional help if concerned.

Q: What is a dangerously low BMI?

A: BMI below 15 is dangerously low and life-threatening. BMI 15-16 requires immediate medical attention. Below 13 is critical and requires hospitalization. Severe underweight causes organ failure, heart problems, and death without treatment.

Q: How is anorexia diagnosed?

A: Anorexia diagnosis requires: significantly low body weight (BMI <17.5), intense fear of gaining weight, distorted body image, and restriction of food intake. Medical and psychological evaluation needed. BMI alone doesn't diagnose eating disorders.

Q: What are health risks of low BMI?

A: Low BMI causes malnutrition, weakened immune system, bone loss (osteoporosis), heart problems, organ failure, infertility, and death. Psychological effects include depression, anxiety, and cognitive impairment. Early treatment is crucial for recovery.

Q: Where can I get help for eating disorders?

A: Contact National Eating Disorders Association (NEDA) helpline: 1-800-931-2237. Seek help from healthcare provider, therapist specializing in eating disorders, or treatment center. Early intervention improves recovery outcomes. You're not alone.