The feeling of a once perfectly fitting pair of shoes suddenly becoming tight leads many adults to ask if their feet have started growing again. It is a common misconception that the bones of the foot continue to lengthen throughout a person’s life. The phenomenon people experience is not biological growth, which involves cellular proliferation and bone elongation, but rather a change in size and shape due to structural and mechanical factors. Adult feet experience changes in volume, length, and width caused by various forces over time. Understanding the distinction between true bone growth and adult foot size fluctuation explains why a person might require a larger shoe size later in life.
When True Growth Stops
The biological process that determines the maximum length of the foot concludes during adolescence. True growth of the long bones, including those in the foot, occurs at specialized areas of cartilage called epiphyseal plates, or growth plates. These plates are situated near the ends of the bone and continuously produce new bone tissue, allowing the foot to lengthen.
Skeletal maturity is marked by the fusion of these plates, where the cartilage fully hardens into solid bone. This fusion typically begins around the end of puberty. Girls usually reach their full foot size around ages 13 to 14, while boys may continue growing until approximately ages 16 to 18. Once the growth plates have closed, the bones in the foot can no longer increase in length.
How Adult Feet Change Size and Shape
After skeletal maturity, bone length remains fixed, but the foot’s soft tissues are susceptible to change, leading to noticeable increases in size, width, and volume over decades. The most common structural change involves the gradual loosening of the ligaments and tendons that support the foot’s arch. This connective tissue laxity allows the arch to slowly flatten, a process known as pronation, which causes the foot to elongate and widen slightly.
Sustained pressure from the body’s weight significantly contributes to this structural flattening. The foot is engineered to support the entire body, and any increase in mass puts greater strain on the foot’s complex network of 26 bones and numerous ligaments. Over time, this increased load forces the structure to spread, causing the foot to lengthen and broaden under the sustained force of gravity. This mechanical change can result in the need for a shoe that is a full size larger than one worn in early adulthood.
Hormonal shifts can also temporarily or permanently alter foot size, most notably during pregnancy. The placenta secretes the hormone relaxin, which is designed to increase the laxity of ligaments throughout the body in preparation for childbirth. This systemic effect includes the ligaments in the feet. When combined with the weight gain of pregnancy, this can lead to the arch collapsing and the foot spreading. Studies indicate that approximately 60 to 70 percent of women experience an increase in foot length or width during pregnancy, with the change often being permanent after delivery.
The protective padding on the sole of the foot also changes with age due to a process called fat pad atrophy. The fatty tissue under the heel and the ball of the foot loses volume and elasticity, diminishing its ability to absorb shock. While this does not make the foot grow, the loss of cushioning can alter foot mechanics and necessitate different footwear for adequate support and comfort. Structural deformities, such as bunions or hammertoes, also represent a change in shape that requires a shoe with greater space, particularly in the toe box.
Practical Steps for Changing Foot Size
Since foot size changes are common, assuming a static shoe size for life can lead to discomfort and foot health issues. Regularly measuring the feet is a straightforward way to address these changes, especially the width. Foot length and width should be measured at least once a year, as size can fluctuate throughout the day due to fluid retention and activity.
Wearing footwear that is too small can accelerate the development of painful conditions. Constricting shoes fail to accommodate the spreading and flattening of the foot, potentially leading to bunions, corns, or ingrown toenails. A proper fit ensures the foot’s structure is adequately supported without compression, which helps mitigate further arch collapse.
When purchasing new footwear, both feet should be measured, and the size of the larger foot should determine the shoe purchased. If a person experiences significant foot pain, persistent swelling, or a rapid, unexplained change in size, consulting a podiatrist is advisable. A foot specialist can assess the underlying causes and recommend orthotic devices or specific footwear to maintain mobility and long-term foot health.