Final answer:
Body fat content varies with gender, age, and physical activity, and is crucial for assessing health risks. The skin-fold test, BMI, and DEXA are different methods for measuring body fat, but BMI may not always be accurate. Visceral fat, especially, is a strong predictor of disease risk.
Step-by-step explanation:
Measuring body fat content is important as it's a predictor of disease risk and varies with sex, age, and activity levels. For women, the optimal fat content is between 20 and 30 percent of their total weight, while for men, it is between 12 and 20 percent. Methods such as the skin-fold test with calipers and Dual-energy X-ray absorptiometry (DEXA) are used to measure body fat.
However, the Body Mass Index (BMI) does not accurately reflect the proportional contents of fat, muscle, and bone, as it is simply a calculation of weight against height. BMI can underestimate or overestimate body fat because it doesn't account for muscle mass, which weighs more than fat mass. Furthermore, fat distribution in the body also influences disease risk, which is why measurements such as waist circumference can be informative. Visceral fat, found in the abdominal cavity, is particularly associated with greater health risks.
It's also noteworthy that gender plays a role in these differences, with men generally having higher muscle mass and lower body fat percentage compared to women. This affects basal metabolic rates across sexes and ages.