The Scale Lies!

Cristina Goyanes, SELF magazine

Those digits can deceive, making you feel pudgy when you're not or giving you false slim-security. Use BMI or body-fat percentage (BFP) to suss out your true fatness. SELF has the skinny on the way that's right for you.

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Who it's for: Athletes or fitness fanatics who might be dubbed overweight by BMI because their muscle mass makes them naturally heavier. BFP is also a wake-up call for "skinny fat" women, whose BMI is fine but who, because their muscle tone is zilch, could have dangerously high body fat, which can increase the risk for diabetes, heart disease and other serious ailments. (Not either? Anyone can use it to gauge her body fat.)

How it works:
The easiest way to get an accurate BFP reading is a skin-fold test. Calipers (they look like long prongs) measure thickness near your hip at and at your thigh and triceps.

Where to get it:
Many gyms offer the test gratis to members, or you can ask your doc to test you. What your number means:
14-20% Oh, yeah! You're athlete-level fit.
21-24% Sweet. You're in great shape.
25-31% Ok, but your health risks may rise; up your strength training.
32+% You're actually obese (even though you may not look it.)

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Who it's for: Workout novices who need to lose a lot of weight in order to get fit, says Pete McCall, an exercise psychologist with the American Council on Exercise. As you shed major pounds, you'll se your BMI go down-and encouraging sign that you're on track. BMI also helps average-weight, average-muscle-tone folks get a snapshot of their health. (To know your actual body fat, you need to use BFP.) But if you're just looking to drop a size, skip this calculator. Replacing a few pounds of fat with muscle won't always change BMI., and you may think you're not progressing when you are are, McCall notes.

How it works:
The formula takes how tall you are and how many pounds you carry, then estimates if you're at a healthy weight.

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Where to get it: What your number means:
18.4 or less Underweight. You actually need a little fat to be healthy.
18.5-24.9 Normal weight. You're in the zone.
25.0-29.9 Overweight. Health risks rise in this range.
30+ Obese. Time for a major body transformation.

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3 CrossFit Total-Body Workouts
50 Healthiest Snacks
6 Secrets to Firing Up Your Metabolism