Frequently Asked Questions.

Body Mass Index (BMI) is a number calculated from your height and weight. It is used as a screening tool to classify adults into weight categories: underweight, normal weight, overweight, and obese.

For adults, a BMI of 18.5–24.9 is considered healthy. This range is associated with the lowest risk of weight-related health problems in large population studies.

Metric: BMI = weight(kg) / height(m)². Imperial: BMI = 703 × weight(lbs) / height(in)².

The same thresholds are used for both sexes, but the health implications can differ. Women naturally have higher body fat percentages at the same BMI as men. For clinical assessment, body fat percentage and other measures are often more informative.

No. BMI does not distinguish between fat mass and muscle mass. An athlete with high muscle mass may have an elevated BMI despite low body fat. In such cases, body fat percentage or waist circumference are more relevant.

For children aged 2–19, BMI is interpreted using age-and-sex-specific percentile charts (CDC or WHO). A child below the 5th percentile is underweight; at or above the 95th percentile is obese.

Older adults may have more body fat at the same BMI as younger adults due to muscle loss with age. Some researchers suggest slightly higher healthy BMI thresholds (23–27) for those over 65.

Yes. Many health organisations, including the WHO, acknowledge that Asian populations face higher cardiometabolic risk at lower BMI values. Alternative cutoffs of 23 (overweight) and 27.5 (obese) are often recommended.

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest to sustain vital functions. TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor to estimate total daily calorie needs.

The Mifflin-St Jeor formula (1990) is considered the most accurate for most adults in systematic reviews. The older Harris-Benedict equation (1919) is still widely used but slightly less accurate on average.

A deficit of 500 calories per day below your TDEE typically results in about 0.5 kg (1 lb) of weight loss per week. Deficits larger than 1,000 cal/day are not generally recommended without medical supervision.

Ideal weight formulas (Robinson, Miller, Devine) estimate the weight at which a person of a given height has the lowest statistical risk of weight-related health problems. These are population-based estimates, not individual prescriptions.

For men: 14–17% (fitness), 18–24% (average). For women: 21–24% (fitness), 25–31% (average). Essential fat is ~3–5% for men and ~10–13% for women.

The Deurenberg formula estimates body fat from BMI, age, and sex: Body Fat % = 1.2×BMI + 0.23×age − 10.8×(1 if male, 0 if female) − 5.4. It is less accurate than direct measurement methods.

All formulas are based on published clinical research and WHO guidelines. Results are estimates with known accuracy ranges — not medical diagnoses. We recommend consulting a healthcare professional for personalised health assessment.

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