Many methods for measuring body fat are notoriously inaccurate, and some leave a huge margin of error!
This should not be construed as medical advice. I am a retired Board Certified Plastic Surgeon.Body Fat Analyzers
do come in different forms and accuracy. However, even the moderately priced units can be extremely valuable as motivation devices. I preferred to keep a reasonably priced unit in my office to demonstrate the value of tracking body fat for my patients to dispel the myth that people needed an expensive segmental unit to achieve goals. Each patient was weighed and an Omron unit used to measure their fat. Technology has moved well beyond with the wireless and smartphone integration.
The scales are quite accurate now for the needs of the typical individual trying to lose weight. If you understand the physics behind the device, more inadequacies come with the variables the user inflicts on their measurements. This is a device dependent on skin conductivity. So a sweaty or wet right after shower body will test different than someone who has dry skin or just having used foot creams or lotions. Trying to keep conditions the same can increase the consistencies of the unit.
Hope this helps,
Michael Bermant, MD
Retired Plastic SurgeonLearn More About Plastic Surgery