What Can Cause the Right Leg to Be Bigger Than Left?

The human body is never perfectly symmetrical. The body is shaped and formed in response to your environment and genetics. Most people have differences in all dimensions whether it's height, width, or diameter in the body parts that come in pairs. This includes arms, hands, legs, feet, eyes and ears. Humans are visually attracted to symmetry and when there is a major difference in a limb it's noticeable. One of the most common discrepancies in the body is in the legs. There can be a few reasons why one leg can be more or less in size than the other.

Overuse/Dominance

• One of the main reasons the right leg could be bigger than the left leg or vice-versa is because of overuse. Humans have a dominant limb used for different functions and activities. If you use a particular limb, like the leg, in excess relative to the other leg, size discrepancies can occur. You can see this in sports with soccer players who kick using their dominant leg and basketball players who jump off on one leg. In sports, when performing a particular movement, the mechanics tend to be the same over and over again. A basketball or soccer player doesn't change their dominant leg they use to kick or jump with which can result in a leg being much bigger.

Underperforming

• This will seem similar to the previous example but it comes from the other end of the spectrum. There are individuals who have leg discrepancies that don't particularly have or use a dominant leg. For example, cyclists and runners use both legs when performing. In a case like this, if one leg is bigger than the other it could be due to a compensation pattern from activity. For various reason, one leg is either weaker or stronger than the other and even though both legs are being used to perform a certain activity, one could be under- or over-performing enough to cause a difference in the size of the leg.

Old Injuries

• If a leg is bigger due to some other reason outside of mechanics, another possibility is an old or even new injury. When you get injured and tissues heal, collagen remodels, scar tissue develops; even small bone changes can occur. Fluid is the medium through which all the nutrients and resources help to heal tissues, many times injured parts of the body can retain fluid and have edema. This can happen even if the injury was several years ago. You notice this when people respond to changes in weather and humidity when they feel it in their joints. Chronic edema from a prior injury can cause a leg to be bigger than the other.

Body Structure

• The body always tries to maintain balance in structure to keep you straight and level with the horizon. This is often confused with being symmetrical where your body actually tries to create symmetry with the outside world not your body parts. We see this in functional scoliosis; for various reasons functional scoliosis can develop in people to compensate for structural changes in the rest of the body. A scoliosis pattern can cause one leg to be bigger than the other because of it's positioning and therefore it's use is much different than the other leg. This could lead to a bigger leg.