Whole-body air displacement plethysmography

Whole-body air displacement plethysmography (ADP) is a recognized and scientifically validated densitometric method to measure the human body fat percentage. ADP uses the same principles as the gold-standard method of underwater weighing but representing a densitometric method that is based on air displacement rather than on water immersion. Air-displacement plethysmography offers several advantages over established reference methods, including a quick, comfortable, automated, non-invasive, and safe measurement process, and accommodation of various subject types (e.g., children, obese, elderly, and disabled persons). However, its accuracy declines at the extremes of body fat percentages, tending to slightly understate the percent body fat in overweight and obese persons (by 1.68–2.94% depending on the method of calculation), and to overstate to a much larger degree the percent body fat in very lean subjects (by an average of 6.8%, with up to a 13% overstatement of the reported body percentage of one individual — i.e. 2% body fat by DXA but 15% by ADP).