While the bones of the foot stop growing in length after skeletal maturity, the overall dimensions—length, width, and volume—often increase significantly over time. This change is not due to bone growth but rather the effect of decades of accumulated stress and structural relaxation. The result is that the shoe size worn in youth is often no longer the correct size later in life.
Understanding Foot Structure Changes
The physical change in foot size is primarily a consequence of the gradual weakening of the body’s soft tissues. The ligaments and tendons that hold the 26 bones of the foot together lose their inherent elasticity over many years. This loss of tensile strength, often referred to as ligamentous laxity, allows the structure of the foot to spread under the constant downward pressure of body weight and gravity.
This structural relaxation leads to a progressive flattening of the medial longitudinal arch, also known as pronation or arch collapse. As the arch lowers, the foot naturally elongates and widens slightly to accommodate the change in shape. Studies suggest that this structural spreading can lead to an increase of at least half a shoe size for many people as they age.
Beyond the structural framework, the protective cushioning on the sole of the foot also changes. The fat pads that lie beneath the heel and the ball of the foot tend to thin out, a condition called fat pad atrophy. This loss of shock absorption alters how the foot contacts the ground, which can change the foot’s functional shape when weight is applied.
Lifestyle and Health Influences on Foot Size
Health-related factors can accelerate structural changes or temporarily increase foot dimensions. Weight gain is a significant factor, as an increase in body mass places exponentially more pressure on the foot’s supporting ligaments and tendons. This added burden accelerates the flattening of the arch, leading to more pronounced lengthening and widening of the foot.
Fluid retention, medically termed edema, is another common cause of increased foot volume, particularly in older adults. Conditions like poor circulation, heart failure, or kidney disease can cause fluid to pool in the lower extremities. This swelling causes the feet and ankles to temporarily increase in size, making previously well-fitting shoes feel restrictive and tight.
Musculoskeletal conditions frequently seen with age can permanently alter the foot’s shape and required shoe size. Deformities such as bunions and hammer toes require shoes with extra width and depth. Complications from diabetes, including poor circulation and nerve damage (neuropathy), can necessitate specialized, wider footwear. This helps prevent injury and accommodate changes in foot contour.
Re-evaluating Your Shoe Size
Because the dimensions of the foot change over time, relying on the shoe size worn in your twenties is often inaccurate. It is advisable to have your feet measured regularly, ideally once a year, to account for structural changes. Foot measurement should be performed while standing, as weight-bearing causes the foot to spread and lengthen, revealing its true functional size.
For the most accurate assessment, new shoes should be tried on later in the day, when the feet are naturally at their largest due to normal daily swelling. If your feet are different sizes, always buy shoes that fit the larger foot. Ensure there is approximately a thumb’s width of space—about 10 to 20 millimeters—between the longest toe and the end of the shoe.
Choosing footwear with adequate cushioning, a wide sole for stability, and proper arch support can help mitigate further structural decline. Properly fitted shoes accommodate the current size and shape of the foot. This is paramount for maintaining balance, comfort, and mobility as the body ages.