150 Pounds of fat and 150 pounds of muscle weigh the exact same, but your scale will not indicate which is which. Even the body Mass Index method will not indicate which is which. We must consider the body fat percentage as a proper indicator of ideal weight. A person with a Mesomorph type structure of a particular height and weight may come off as reading as obese by the BMI standard and scale weight. But he may be at about 6% body fat and very muscular. The same goes with an individual that has changed his body composition from higher fat to higher muscle. He may still weigh 160 lbs, but his first weight was at 25 % fat and the second at 12 %, the difference is his weight at 12% is denser muscle and a loss in fat weight. He may even weigh more at 12% fat because of his increase in muscle.
We must consider the body fat percentage as a proper indicator of ideal weight
There are many ways to accurately determine your fat content. some require expensive complicated equipment like Hydrostatic (underwater) testing, bioelectric Impedance, CT scans, and Air Displacement Plethysmography. A simpler , cheaper and accurate method is using skin calipers. A skin fold reading is usually taken at 3 bodily locations that are different for men and women.
A healthy body fat percentage for women is considered at between 18 to 22%. For men at 12 to 15%. A 200 lb. woman at 33% fat would have 66lbs. of fat and 134 lbs. of lean weight. The ideal weight at 18% fat would be the lean weight 134lbs. divided by 0.82 (100% – 18% fat) which will be 166.4lbs