Body-fat monitors/scales send small, harmless electrical pulses through a user's body to gauge their body weight/density. Many body-fat scales display both body-fat percentage and body mass index (BMI). BMI is a rough estimate of body composition that is calculated using a person's height and weight. According to the Centers for Disease Control and Prevention, BMI can be useful for determining whether a person is overweight, but it's not a foolproof method.
For example, athletes with a great deal of muscle may have a high BMI reading even though they don't possess a lot of body fat. Similarly, body-fat percentages look at how much of a person's body is composed of fat. While both of these calculations can be useful, experts caution that they do not provide a complete picture of an individual's health. Experts say an individual's waist circumference, hip-to-waist ratio, blood pressure and cholesterol levels are also important indicators of health.
Body-fat scales tend to be off by as much as 5 to 10 percent. Muscle & Fitness Hers magazine consults Dr. Richard Pierson Jr., a professor of clinical medicine at St. Luke's-Roosevelt Hospital of Columbia University, on a number of body-fat measurement methods. He acknowledges that individual readings may not be accurate, but points out that body-fat scales are a good way to monitor changes in body fat over short periods of time.
Scale readings can be thrown off by a number of factors, such as how much water you drink, whether you have a full bladder or whether you have foot calluses. Cedric Bryant, chief exercise physiologist for the American Council on Exercise, tells WebMD that body-fat scales should be used under similar conditions each time, such as time of day and fluid and food intake, noting that even a woman's menstrual cycle can affect readings. "However, with all this factored in, these scales are an easy, at-home way to keep track of your weight and fat-loss progress," says Bryant.
An already popular manufacturer of digital bathroom scales, EatSmart recently made its foray into the body-fat scale scene with its EatSmart Precision GetFit Digital Body Fat Scale (*Est. $60), a considerably affordable body-fat scale compared to others.
Like most body-fat scales designed for home use, the Precison GetFit uses a harmless electrical impulse, called bioelectrical impedance analysis (BIA) to determine the user's body composition. Body-fat scales in general have been found to be less accurate than more complex body-fat measurements, such as hydrostatic weighing (water displacement method), although these techniques aren't practical for regular use. However, users say because it offers consistent readings, it's a good measurement tool for tracking your weight loss or muscle-building progress over time.
The EatSmart Precison GetFit calculates not only weight and body fat, but body water, muscle and bone mass as well. It features a large, 3.5-inch LCD display that's easy to read, even in dim lighting conditions thanks, to its bright backlighting. Like other EatSmart scales, the GetFit does not require a tap-on before use for calibration. Instead, the scale activates and calibrates automatically when the user steps on the platform.
At just 4.5 pounds, the GetFit scale is lightweight and capable of storing data for up to eight users. Owners appreciate this functionality, noting that it's easy for multiple family members to track their weight loss progress independently without the need to write down their stats each day.
On the downside, the GetFit scale depends on some external data, which users must input -- height, for instance -- in order to come up with body composition calculations. The user manual offers explanations for which body type to use (athletic male, male, athletic female or female). Some users say these descriptions are not accurate. Because of this, users may need to adjust their settings to find the initial readings most consistent with those obtained from other measurement tools in order to get the most accurate readings possible.
We found a number of recommendations for various Omron body-fat scales and body-composition monitors. The Omron Body Fat Monitor and Scale HBF-400 (*Est. $45) performs decently in one independent test from Australia. It has a weight capacity of 330 pounds, measured in 0.2-pound increments and measures body fat in 0.1-percent increments. About 550 owners contribute to an average rating of 4 stars out of 5 on Amazon.com, although some reviews appear to be referring to an older model.
Users at Amazon.com are generally impressed with the Omron HBF-400 scale, especially considering its price. In fact, several owners compare it to similar Tanita scales, noting that it stores data for more users and is less expensive. Reviewers acknowledge that the body-fat measurement is not accurate, but the Omron HBF-400 does offer consistent readings. Several owners point out that changes over time are more important than accurate readings, so they don't see this as a major concern.
That said, athletes should be aware that the lack of an "athlete" setting means body-fat readings will be higher than the true reading, because this scale can't account for added muscle mass. Users also point out that you'll want to read the user manual to understand how the scale works, because it can be complicated to use initially.
The Omron Full Body Sensor Body Composition Monitor and Scale HBF-510W, HBF-514C and HBF-516B differ slightly in function but have more advanced features than the Omron Body Fat Monitor and Scale HBF-400. All offer hand grips for full-body measurement. The Omron Body Composition Monitor and Scale HBF-510W (*Est. $65) is the simplest of the three, offering measurements of body-fat percentage, body mass index, skeletal muscle, visceral fat and body weight for up to four users. The Omron Body Composition Monitor and Scale HBF-514C (*Est. $70) offers the same measurements plus resting metabolism and body age. Unlike the HBF-510W, it has a 90-day memory. Finally, the Omron Body Composition Monitor and Scale HBF-516B (*Est. $80) has a 180-day memory.
The Omron Full Body Sensor Body Composition Monitor and Scale HBF-510W earns an average rating of 4 stars out of 5 in nearly 120 reviews at Amazon.com; likewise, the Omron Body Composition Monitor and Scale HBF-514C earns a similar average rating in about 155 reviews. Feedback across all models is similar, with most owners saying these scales are accurate and consistent and a few detractors who say otherwise. All three have a 330-pound weight capacity measured in 0.2-pound increments and are backed by a one-year warranty.
For serious athletes, the Tanita Ironman Segmental Body Composition Monitor BC-558 (*Est. $345) may be worth a look. Like most of the Omron scales, which rely on an electrical current that starts at the feet and runs through the lower body, the Ironman scale includes handles to analyze the upper body. The handles are retractable and are stored on the side of the scale when not in use.
The Tanita Ironman Segmental Body Composition Monitor BC-558 tracks weight, body-fat percentage, body water, muscle mass, bone mass, metabolic age and other weight data. This scale may be overkill for the average user, but testers at Women's Health magazine generally like the Tanita Ironman Segmental Body Composition Monitor BC-558 and all the information it tracks, including metabolic age. "You get a snapshot of your overall health, not just your poundage," write the editors.
A handful of owners posting to Amazon.com give the Tanita Ironman Segmental Body Composition Monitor a 4.5-star rating, but most acknowledge that the scale can be overwhelming to the average user. Additionally, one reviewer says visceral fat is one of the most crucial measurements, and cheaper Tanita models offer this same function. U.S. News and World Report staff writer Sarah Baldauf compares readings from the Tanita Ironman Segmental Body Composition Monitor BC-558 with measurements from a Bod Pod (an advanced method of underwater weighing that doesn't require subjects to get wet). In this instance, the Tanita's readings differ by just one-tenth of a percent. The Tanita Ironman Segmental Body Composition Monitor BC-558 runs on four AA batteries and has a 90-day warranty.