Body fat fallacies and facts

Philip J. Goscienski, M.D.

December 2009

"You can never be too rich or too thin." Most folks would probably agree with the first part of that old cliché but the second is biologically off the mark. Body fat is a curse if you're carrying around too much of it but without a minimum amount of body fat our metabolism would go haywire. The ideal amount for a 150-pound man is approximately 21 pounds or 14 percent of total weight. Women need a little more — about 25 pounds (21 percent) for a 120-pound female.

For the frustrated majority of us who passed those numbers by the time we left high school we can take some comfort in knowing that nature allows for a range of several pounds in both directions. An additional few percent is acceptable. Since every method for measuring body fat is subject to error it's pointless to worry about fluctuations of a pound or two. After all, the contents of a full bladder weigh nearly a pound, skipping dinner can amount to almost as much and we can sweat away another pound working for a few hours in high heat and humidity.

A minimum amount of body fat is critical for several reasons but two are especially important: fertility and insulation.

Physicians who specialize in sports medicine are well aware that some highly trained female athletes stop menstruating, in effect becoming temporarily infertile, when their percentage of body fat drops below the normal low limit. The ability to conceive, carry, deliver and breastfeed a child is an enormously complex process. Success depends on the mother's ability to provide her infant with energy and in times of severe food scarcity both mother and infant would depend on stored energy: fat.

Fat is a good insulator that protects us from cold. Devotees of Calorie Reduction deliberately take in about 80 percent of their estimated caloric needs in an effort to live longer. Without insulating fat they need more clothing to remain comfortable even in moderate weather.

For the huge (pardon the pun) majority of us the tape measure is a better tool than the scale. The medical term for a big belly is central adiposity and it is waist circumference, not just body weight that matters. For women, the ideal waist circumference is 32 inches or less; for men it is less than 35 inches. As those numbers go up so does the risk of heart disease and type 2 diabetes.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.