Childhood Obesity (Obesity Level) Assessment
Calculate the obesity level (%) for school-age children (ages 5–17) from sex, age, height and weight, and classify as underweight, normal, or mild / moderate / severe obesity. Standard weight by height is shown at the same time.
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Input
Based on the School Health Statistics Survey method (standard weight by sex, age and height), this tool assesses the degree of obesity for school-age children aged 5 to 17. It cannot be applied to infants and toddlers.
Result
Obesity level of a 10-year-old Boy
+14.9%
Assessment: Normal
Assessment
Normal
Standard weight by height
34.8 kg
Measured weight
40.0 kg
Obesity level = (measured weight 40.0 kg − standard weight 34.8 kg) ÷ standard weight × 100 = +14.9%(difference from standard weight: +5.2 kg (over))
Assessment categories by obesity level (school age)
| Category | Obesity level range |
|---|---|
| Severely underweight | −30% or below |
| Underweight | over −30% to −20% |
| Normal (applies) | over −20% to under +20% |
| Mild obesity | +20% to under +30% |
| Moderate obesity | +30% to under +50% |
| Severe obesity | +50% or above |
How it works
- Obesity level (%) = (measured weight − standard weight by height) ÷ standard weight by height × 100. The larger the positive value, the heavier the child is compared with standard; a negative value indicates a tendency toward being underweight.
- Standard weight by height is obtained from the linear formula 'standard weight = a × height (cm) − b'. The coefficients a and b use representative values from the School Health Statistics Survey method (standard weight by sex, age and height), which applies to school-age children aged 5 to 17. It cannot be applied to infants and toddlers.
- As a rough guide, +20% or more is mild obesity, +30% or more is moderate obesity, +50% or more is severe obesity, −20% or below is underweight, −30% or below is severely underweight, and anything in between (over −20% to under +20%) is normal.
- Because the coefficients switch by age, when a birthday changes the school grade or age, the obesity level can change even for the same height and weight. Enter the full (completed) age used in school health checkups.
- For adults, other indicators such as BMI and body fat percentage are used. Because physique during the growth period is greatly affected by individual differences and growth spurts, it is important not to judge based on a single point-in-time value alone.
- The results of this tool are a guide for health management and are not a diagnosis or medical treatment. If you are concerned about your child's obesity or being underweight, do not judge on your own—consult a specialist such as a doctor or registered dietitian. For the latest standards, please check materials from Japan's Ministry of Health, Labour and Welfare and the Ministry of Education (Japanese Society of School Health).
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