Are you a greyhound or a St. Bernard?

Philip J. Goscienski, M.D.

April 2007

Get to know your body type — and love it. The genes that you received at conception determined the basic shape and size of your body: short or tall; small-boned or large-boned; long, thin muscles or shorter bulky ones. You can't change those inborn features of your frame any more than you can change your hat size. Let it be a reason for rejoicing, not for frustration.

Among those famous long-distance runners from Kenya, no amount of weight training could convert them into Mr. Universe contenders. In contrast, the Schwarzenegger types with a heavy frame and bulky muscles can usually add to their muscle mass easily with training. Most of us are somewhere in between these two types, well designed for the kind of lifestyle that existed in the Stone Age. Our distant ancestors were slender enough to dissipate heat on the sunny savannah, muscular enough to survive the rigors of life with few or no tools.

Light-framed greyhound types have a predominance of slow-twitch muscle fibers that make them good long-distance runners. Big-boned St. Bernard types have a predominance of fast-twitch muscle fibers that allow them to make rapid lifting movements. Persons of medium build have almost equal numbers of fast-twitch and slow-twitch muscle fibers. Those slender marathoners have as much as 82 percent slow-twitch fibers and competitive swimmers 74 percent. No amount of training can change those ratios.

Interestingly, weightlifters don't have a large excess of fast-twitch fibers. However, their muscle fibers can enlarge, whereas those of elite marathoners and swimmers cannot. In other words, persons with the bone structure and muscle type of distance runners can never "bulk up," while those of medium- or large-framed persons can add several pounds of muscle in only a few months of strength training.

Don't confuse basic body types with apple and pear shapes that describe the manner in which women and men accumulate fat. The excess abdominal fat of a man gives him the apple shape. It melts off quickly because nature designed it to be a source of short-term energy, instantly available when he needed to go without food while protecting the band or searching for food. A woman's accumulation of fat on the thighs has a different purpose. It's meant to sustain a long pregnancy and an even longer period of lactation, so it melts off slowly, the lament of every woman who has tried to lose it. That's why couples shouldn't expect to get the same results when they diet, even when their calorie intake and activity are almost identical.

During the Stone Age both men and women could put on a modest amount of fat during times of food abundance in order to make it through times of scarcity. Our modern bodies can do the same, except that we are living in perpetual abundance with no fear of famine. Nature never intended for our bodies to lug around 50 pounds or more of fat for years at a time but nearly a third of Americans are doing just that.

Whatever your body type, it has unique characteristics, so compare it with the ideal you, not someone else.

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.