Many fitness professionals find themselves working with people who are healthy and lean, but who want to become even leaner.

"We've been working together for three weeks now," you explain to the manager at the fitness center where you work. "She has been a dancer since she was a kid, but has never worked out in a fitness center before. I think she looks great, and when I measured her body composition, she is only 16 percent fat. But she says she has gained 3 or 4 pounds over the past two years, and she insists she needs to lose at least 5 pounds to look great for teaching. She is asking all of these questions about dieting and weight loss. How low do I help her go? How thin is too thin? I don't think she has an eating disorder, but she sure does know how many calories are in every bite of food she eats."
Many fitness professionals find themselves working with people who are healthy and lean, but who want to become even leaner. Some of these people want to improve performance in sports such as running or cycling, where less body fat can translate into faster times. Others want to achieve a lean physique to enhance their ratings in sports or professions where appearance is part of the evaluation, such as gymnastics, diving, dancing, figure skating, body building or modeling. Some may need to reach a specific weight to qualify for a certain activity, such as lightweight rowing or a lower weight class in wrestling. And some may just be obsessed with food and weight. Here are some issues fitness professionals often confront as they help the already lean lose more weight.

How helpful are body composition estimates?

Body composition is more helpful than weight or body mass index (BMI) for setting weight-loss goals or evaluating body composition changes in response to training. We tell clients that we "measure" body composition, but remember that these numbers are really estimates. Even underwater weighing, one of the most accurate estimates, can over- or under-estimate body fat by several units, especially if residual lung volume is not measured. Bioelectrical impedance measures can fluctuate with a client's hydration status. A client found to be 15 percent fat may actually be anywhere from 11 to 19 percent fat. This huge range introduces a measure of uncertainty into any calculations you may be making about how much body fat a given client can afford to lose. What can you do about this inaccuracy? First, perform body composition estimates as accurately as possible. Second, use the same test each time you need a body composition estimate for a particular person. Third, explain to your clients that body composition measures have limited accuracy. And lastly, consider using skinfold measures as stand-alone measures. Changes in skinfold thickness will indicate changes in the thickness of subcutaneous fat at the measured sites.

How can you tell if a client's goal weight is reachable?

Setting a goal weight is tricky because weight loss rarely proceeds as it should, even with extra exercise and dieting. Set goal weights a bit on the high side, if possible, especially if the client has never succeeded in achieving that particular goal weight in the past. Recognizing the error in body composition scores, you may wish to calculate an ideal weight range, rather than a single number. If clients' goals seem unrealistically low, tell them so.

Refer diet questions to a dietician

If you find that your clients have a lot of questions about dieting and food, refer them to a sports medicine dietician. (Find a dietician in your area on the American Dietetics Association website at www.eatright.org.) While it is fine for you to repeat general, mainstream advice (eat more fruits and vegetables, eat less junk food), you exceed your scope of practice if you start prescribing specific meals or supplements, or give dietary recommendations for clients' medical conditions. If you suspect your clients are too obsessed with food and appearance, in a tactful way, let them know your specialty is helping people improve their health and performance, not struggle with food. A good dietician will help you assess the likelihood that your client needs professional counseling, and can help facilitate a referral.
References Clark, N. Nancy Clark's Sports Nutrition Guidebook. Human Kinetics: Champaign, Ill., 2003. Kleiner, S.M., and M. Greenwood. Power Eating: Build muscle, boost energy, cut fat. Human Kinetics: Champaign, Ill., 2001. McArdle, W.D., F.I. Katch and V.L. Katch. Sports & Exercise Nutrition. Lippincott, Williams & Wilkins: Philadelphia, Pa., 2005.