Body Mass Index (BMI)
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Body-mass index is a measure of “relative weight,” in other words, how much you weigh relative to your height. It has essentially supplanted the older Metropolitan Life Insurance weight-height tables of “ideal weight.” The formula for BMI is in metric units: kilograms per meter-squared.
Unlike older tables, BMI does not attempt to adjust ideal weight for frame size. A BMI of less than 18.5 is underweight, 18.5- 24.9 is normal weight, 25-29.9 is overweight, 30-39.9 is obese, and 40+ is severely obese (usually 100+ lbs over ideal weight).
Experts say the old height/weight charts aren’t necessarily the best way to determine whether a person needs to lose or gain weight. Instead, they use as a guide Body Mass Index (BMI), a measure of how much fat you’re packing. If you are curious about your BMI and math is not your strong suit, you can find BMI calculators online.
Here’s what the numbers indicate:
Underweight: Below 18.5
Normal: 18.5–24.9
Overweight: 25.0–29.9
Obese: 30.0 and above
Morbidly Obese: 40.0 and above
Body mass index (BMI) measures the relationship (or ratio) of your weight to your height. It is an estimation of body composition based on the notion that your body weight should be proportional to your height.