Body composition

Identify your state of fitness and set a course: 7 calculators to understand your body beyond the number on the scale.

IMC — indice de masse corporelle Poids/taille². Le premier repère, à compléter par d'other measures. TDEE — total energy expenditure How much your body burns each day depending on your energy level'activité. BMR — métabolisme de base L'minimum energy to maintain your vital functions at rest. Fat mass percentage Estimate by measurements (US Navy) or impedance. Lean/muscle mass Your mass excluding fat — useful for targeting your protein intake. Ideal weight (Lorentz, Creff) Several historical formulas with their limits. Waist/hip ratio Fat distribution indicator, linked to cardio-metabolic risk.

Why not just rely on BMI

BMI is a useful benchmark, but it does not distinguish fat mass from lean mass. A muscular athlete can have an “overweight” BMI without excess fat, and conversely a sedentary person can have a “normal” BMI with high fat mass. Combining BMI + waist circumference + body fat rate gives a much fairer vision.

How these calculations work together

The BMR (basal metabolism) is the base: it is the energy that your body consumes at complete rest. Multiplied by your activity level, we obtain the TDEE (total expenditure). From there, you know what amount of calories to aim for: maintenance (= TDEE), loss (TDEE − deficit) or intake (TDEE + surplus).

The waist-to-hip ratio and the fat mass percentage are independent of weight and provide clues about body composition. lean mass is useful for calibrating your protein intake (≈ 1.6–2.2 g/kg of lean mass depending on your objectives).

What regularity of measurement?

Once a month is enough for estimates (fat mass percentage, waist/hip ratio). The TDEE must be recalculated as soon as your weight or activity changes significantly (> 3 kg or change in sports routine).

À consulter aussi

Hub : tous les calculateurs 23 outils sportifs gratuits Calcul des macros Pilier suivant : nutrition Déficit calorique Une fois votre TDEE connu Besoins en protéines Basé sur votre masse maigre

Questions fréquentes

Le BMR est l'energy consumed by your body at complete rest (vital functions). The TDEE also includes all your daily activity (work, sport, travel). TDEE = BMR × activity factor.

No, not alone. A muscular athlete has a high weight without excess fat — their BMI may incorrectly indicate “overweight”. Combine with body fat percentage and waist circumference.

None are universally valid. Lorentz takes sex into account, Creff morphology. These formulas date from the 60s and 70s and do not reflect the diversity of body types. Use as a benchmark, not a strict objective.

Yes. Several studies (WHO, Lancet) show it as a predictor of cardio-metabolic risk, independently of BMI. Reference threshold: < 0.85 for women, < 0.90 for men.