Body weight alone tells you very little about whether a person is carrying excess fat, under-muscled, or both. Two people can weigh 165 pounds and have completely different health profiles. The four measurements below are the ones clinicians actually use, and each has a specific blind spot worth knowing before you trust the number.<\/p>\n\n\n\n
| Metric<\/th> | Formula<\/th> | Healthy range<\/th> | Blind spot<\/th><\/tr><\/thead> |
|---|---|---|---|
| BMI<\/td> | weight (kg) ÷ height (m)²<\/td> | 18.5-24.9<\/td> | Ignores muscle mass entirely<\/td><\/tr>\n |
| Body fat %<\/td> | Varies (DEXA, calipers, BIA)<\/td> | 14-24% men, 21-31% women<\/td> | Consumer scales have 3-8% error margins<\/td><\/tr>\n |
| Waist-to-height ratio<\/td> | waist ÷ height (same units)<\/td> | Below 0.5<\/td> | Requires correct waist measurement point<\/td><\/tr>\n |
| Waist-to-hip ratio<\/td> | waist ÷ hip<\/td> | Below 0.90 men, 0.85 women<\/td> | Less predictive of visceral fat than WHtR<\/td><\/tr>\n<\/tbody><\/table><\/figure>\n\n\n\nWhy Waist-to-Height Replaced Waist-to-Hip in Most Research<\/h2>\n\n\n\nThe shift happened because waist-to-height ratio works with a single cutoff \u2014 0.5 \u2014 across every age group and both sexes. A 5’4″ woman with a 34-inch waist sits at 0.53, above the line. A 6’2″ man with the same 34-inch waist sits at 0.44, comfortably below it. Waist-to-hip ratio requires different thresholds for men and women and performs worse in predicting cardiovascular events in several large cohort studies.<\/p>\n\n\n\n The 0.5 cutoff is also easy to act on. If you measure your raw waist circumference and your height in the same units, the rule is: if the number is more than half your height, you’re carrying a level of central fat associated with elevated risk.<\/p>\n\n\n\n Is BMI Useless Then?<\/h2>\n\n\n\nNo, but it’s a screening tool, not a diagnosis. BMI’s failure mode is specific: it misclassifies muscular people as overweight and misclassifies people with low muscle mass and normal weight as healthy. A 5’10” athlete at 200 pounds reads BMI 28.7, in the “overweight” band, while carrying 12% body fat. The same BMI in an office worker with 30% body fat means something very different.<\/p>\n\n\n\n For population-level screening it works fine because those errors cancel out across thousands of people. For an individual, pair it with a waist measurement. If BMI says 27 and waist-to-height says 0.44, the BMI number is probably the misleading one.<\/p>\n\n\n\n A Worked Example<\/h2>\n\n\n\nTake a 41-year-old woman, 5’6″ (66 inches), 150 pounds (68 kg).<\/p>\n\n\n\n
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