Photo: Best Life

Q: What's the best way to weigh yourself?

A: We brought our FAQ's about BMI, body comp, and pounds to two Best Life nutritionists, Stephanie Clarke, M.S., R.D. and Willow Jarosh, M.S., R.D. Before jumping on that scale, read their list of weight dos and don’ts.

Do understand what your numbers mean.

Weight isn't the only measurement that matters, but it's one of the most widely-used guidelines for assessing personal health (and for determining which countries have the highest obesity rates). Clarke and Jarosh use the Best Life formula to generate what they call "an average healthy weight." For women, start with 100 pounds and add 5 pounds for every inch over 5 feet. Expand this to include a 15% window (plus and minus) to account for different body types. So a healthy weight for a woman who is 5'5" would be within the range of 107 to 144 pounds. The Centers for Disease Control uses body mass index, or BMI, to determine that the healthy weight range for a woman who is 5'5" tall is 111 to 150 pounds. (use the CDC's calculator to see where you fit in).

Don't freak out if you're on the high end of the healthy weight even though you came in third in the Labor Day 5k.

"Athletes or others with a lot of muscle mass might have a higher BMI," says Clarke. A third measurement, body composition, measures fat versus lean muscle mass. This is done using either calipers (small tongs that pinch the skinfolds) or bioelectrical machines. This is very difficult to do without proper equipment (see why Bob Greene warns about relying too heavily on this measurement), so to get the most accurate body comp reading, talk to your doctor or fitness trainer.

Do know how to define your personal healthy weight.

In their private nutrition practice, Clarke and Jarosh help new clients determine what weight means to them by getting them to think about the weight at which they feel most energetic and healthy, and what being at their ideal weight allows them to do (for example, keep up with their Weimaraner puppy). Read more advice from Bob Greene on finding your perfect goal weight.

Don't weigh yourself all the time.

When starting a new weight loss plan, Bob Greene recommends waiting to weigh yourself for a full month. "Numbers can fluctuate in the beginning, especially if you've been following an extreme diet program," says Clarke.  The Best Life team recommends weighing in once a week--no more than that--at the same time of day. "For the most accurate assessment, stepping on the scale first thing in the morning without any clothes on is the way to go," says Clarke. Check out this checklist for tips on when and how to weigh.

Do rely on other motivators besides pounds.

Clarke and Jarosh say that many of their clients find numbers on a scale to be the easiest and most reliable way to tell if their hard work is paying off. But they've also talked to people who put more stock into goals like squeezing into too-tight clothing ("fitting into my skinny jeans" is a yogurt commercial cliché for a reason). "We had one client who developed sleep apnea after gaining weight, and one of his biggest motivators was not having to sleep with his CPAP mask, which is very uncomfortable,'" says Jarosh.  Many studies have shown that losing excess weight has major benefits that go beyond health -- read about them here.