For their study, the researchers analyzed data from 4,252 people aged 20 to 49 enrolled in a national U.S. health and nutrition survey. All had a technician measure their height, weight and waist circumference. Their body-fat percentage was also assessed via “bioelectrical impedance analysis,” or BIA, which works by applying a small, harmless current through the body, measuring resistance as it passes through the body’s tissues. It estimates total body composition, including fat-free mass and total body water.
