How Well Do Body Composition Scans Work?

Body Comp Scan

Clients can prepare clean meals, hydrate sufficiently, and train properly, yet still find that truly positive results elude them. What other resources may prove useful? What might trainers suggest? Learn how a body composition scan can serve as a helpful adjunct to both weight loss endeavors and personal training.

Body Scans, Stats and Predictions

Body composition scans, a new and innovative assessment that requires very little of a client’s time, aims to measure the bone, fat, and muscle makeup of one’s body. Such an analytical rendering can benefit both the client and his trainer when embarking upon a new workout program. A clearer understanding of one’s body helps to identify problem areas, making goal-setting even easier.

Trainers often counsel clients not to obsess about a number on the bathroom scale, since lean muscle mass does in fact weigh more than adipose (fat) tissue, and can often account for weight gains at the start of exercise programs. This concept, while often a tough sell, is corroborated in a body scan.

There are a few different technologies out there with slightly different approaches to measuring body composition. Popular brands have both in-home and gym models of varying degrees of complexity and offerings. This body scan works by sending harmless electrical impulses throughout the body, known as bioelectrical impedance analysis (DSM-BIA).

While not directly measuring body fat, such scans make use of formulas to surmise a body’s composition of fat, muscle, water, etc. based on the conductivity of the water it detects; different tissue will vary in the amount of electricity it can conduct based on the content of water it contains.

Some budget models of these scanners only send impulses through the hands like this Omron, and others, just the feet. Higher-end models of total body comp scanners like InBody will also send impulses through both the hands and feet, which looks like a large stand-on scale with handles.

Accounting for human nature when making even educated guesses, we must expect a certain deviation of standard in terms of error, and not assume 100% accurate predictions.

The Imaging Process

Further, other commercial scanners provide a 360-degree imaging scan of the entire body, such as the Shape Scale. While this does not utilize bioelectrical impedance to estimate fat/lean mass, it gives you an actual photographic representation of fat versus muscle, so that progress can be tracked over time.

In fitness and health centers that offer this type scanning assessments to their clientele, the client stands on a platform with arms outstretched and hands clenched into loose fists. The platform then begins its 360-degree rotation, accomplished in under a minute. Through the use of a harmless infrared light that reflects off the body, the machine comes up with digital measurements similar to those taken with a tape measure. The difference between this analysis and manual measurements that trainers take involves greatly reducing the aspect of human error. This 3-dimensional model of a client’s body helps in quantifying surface area and volume; all of these values combine to predict a very close approximation of an individual’s body composition.

While such an analysis must still take into account some small degree of error, the efficacy of these scans piqued the interest of the National Institutes of Health. The NIH subsequently approved a tremendous amount of funding to two separate body composition companies, in an effort to expand the industry’s scope of knowledge on body scanning research. Clearly this leading icon feels strongly about the scanners’ potential for commercial use and eventual availability at more fitness centers and nutritionists’ offices.

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Many Factors Influence Body Composition Scan Results

During a workout, bodily fluids get concentrated in the area upon which the exercises focus, by way of providing nutrients and removing waste products. Following a workout, core body temperature increases, thereby lowering electrical impedance and decreasing the apparent percentage of body fat. Conversely, a cooler body temperature elicits an increase in electrical impedance, which reflects a lower amount of fat-free mass.

Total body water (TBW), estimated through electrical impedance, can help to calculate fat-free mass. Scientists base these calculations on the assumption that water comprises 73-77% of the body’s fat-free mass, with bone, muscle, organs, etc, remaining. A key conceptual problem lies in the frequently-misunderstood fact that fat-free mass (or lean mass) and lean muscle mass are not interchangeable terms, an error commonly made even by fitness professionals. Lean mass/fat-free mass is anything that is not adipose tissue, and lean muscle mass is only the percentage of that lean mass that is muscle. Clients must understand that an increase in fat-free mass does not necessarily mean they have put on more lean muscle tissue.

 “Success” Best Assessed by the Client’s Perception

Many professionals feel that body scans may not accurately reflect either body composition or a client’s progress. The most important way of assessing progress should take into consideration how the client “feels” in his own skin. After that, trainers might consider the use of photos and circumference measurements to assess periodic progress. The client can best judge how his clothing fits, while also honestly looking at improvements in his fitness abilities, strength, energy, sleep patterns, and meal planning.

Finally, ask the clients directly, “How do you feel about yourself and your past efforts as you move towards your goal?” This idea, beyond all other measuring tools, helps to empower the client, providing him with a sense of mastery over his process towards an ultimate goal, and the maintenance beyond.


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Cathleen Kronemer is an NFPT CEC writer and a member of the NFPT Certification Council Board. Cathleen is an AFAA-Certified Group Exercise Instructor, NSCA-Certified Personal Trainer, ACE-Certified Health Coach, former competitive bodybuilder and freelance writer. She is employed at the Jewish Community Center in St. Louis, MO. Cathleen has been involved in the fitness industry for over three decades. Feel free to contact her at [email protected] She welcomes your feedback and your comments!