Here is a quick cut and paste on measuring body fat and safe levels:
Skinfold Caliper - can be done by most trained health professionals or fitness professionals. It is quick and non-invasive. Usually requires taking three measurements at different sites of the body (tricep, abdomen, upper thigh) then plugging these numbers into a formula. May be 7-8% error in measurement. Measurements can be affected by the skill level of the professional taking them and are not accurate for obese patients.
Bioelectrical Impedance - fairly inexpensive scales or handheld devices are now available for purchase and use in the home. The device sends an electrical impulse through the body (you won't feel a thing) and measures the body fat by how easily the impulse is transmitted. These devices are good to give you a sense of how your body fat may change over time but may not be highly accurate. Readings can be easily affected by hydration status, obesity, and muscle mass. Muscular athletes typically get higher than actual results.
Underwater Weighing - this requires that you be completely submerged in a tank of water. While underwater you must breathe out all air from your lungs. It requires specialized equipment and highly trained technicians. When performed correctly it as a less than 2% error rate.
DEXA - stands for dual x-ray absorptiometry. Is quick and easy but requires expensive equipment typically only found in hospitals and research centers. It takes an x-ray of the body that shows fat, muscle, and bone mass based on differing densities. It has good accurracy.
Bod Pod - still fairly new on the market but seems to have great promise. Studies show it to be comparable to underwater weighing and DEXA. The major advantages are that it is fairly inexpensive equipment, requires little training to operate, comfortable for people of all shapes and sizes, and is quick and easy. All you do is have a seat in an enclosed egg-shaped pod.
Minimum body fat recommendations:
Men: 3-6%
Women: 12-15%
Average body fat:
Men: 15%
Women: 24-26%