BMI

Illustration: mckibillo

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Day 16: Calculate Your BMI
Divide your weight in pounds by your height in inches squared. Then multiply that figure by 703.

The result is your body mass index—a rough assessment of how much fat you're carrying on your frame. A BMI between 25 and 29.9 indicates you are overweight; 30 or greater means you are obese. But if your number is over 25, keep in mind this encouraging fact: Dropping just a fraction of your weight can have a dramatic impact on your overall health.

Lose 5 percent of your body weight and you can...
improve your body's ability to use insulin (the hormone that moves glucose into cells to be metabolized), lowering your risk of type 2 diabetes.

Lose 11 percent of your body weight and you can...
significantly lower your blood pressure, reduce your risk of dying from cardiovascular disease by 21 percent, and slash your risk of dying from all causes by 25 percent.

Lose 16 percent of your body weight and you can...
experience a nearly threefold increase in your levels of vitamin D, which may be key to helping prevent everything from migraines to Parkinson's disease.