The experience of noticing a change in shoe size long after adolescence is common, particularly for people in their 30s. A shoe that once fit perfectly may suddenly feel tight, leading many to wonder if their feet are still growing. While the sensation of feet “growing” is valid, it is not the result of a biological growth spurt. The change relates to structural and soft tissue alterations that increase the foot’s length and width, often requiring a different shoe size.
The Limits of Skeletal Growth After Puberty
The biological process of bone lengthening is finalized by the end of puberty, well before the age of 30. This growth is driven by specialized areas of cartilage called epiphyseal plates, or growth plates, located near the ends of long bones. These plates actively produce new bone tissue, allowing the foot’s structure to increase in size throughout childhood and adolescence.
Once a person reaches skeletal maturity, typically between the ages of 13 and 17, these growth plates harden and fuse into solid bone, a process known as epiphyseal closure. At this point, the 26 bones that make up each foot can no longer become longer through natural growth. Therefore, any change in foot size experienced in adulthood is not due to the bones themselves increasing in length, but rather a reshaping of the foot’s architecture.
Non-Bony Factors That Change Foot Size
The primary mechanisms behind adult foot size change involve the gradual weakening and stretching of the soft tissues that support the foot’s structure. Decades of impact and the unrelenting pull of gravity place constant stress on the ligaments and tendons. This wear-and-tear causes supporting tissues, like the plantar fascia, to lose elasticity over time.
As the ligaments become lax, the arch of the foot begins to flatten and collapse, a process called pronation, which increases the foot’s length and width. For example, a “fallen arch” causes the foot to splay out, which can easily translate to an increase of a half-size or more in shoe length.
Another significant contributor is fluctuation in body mass, as greater body weight increases the pressure exerted on the feet with every step. This extra load forces the feet to flatten and widen as they bear the additional strain. Weight gain can also add tissue to the feet themselves, causing them to appear larger.
Hormonal shifts can also temporarily or permanently alter foot structure, most notably during pregnancy. The hormone relaxin, released to prepare the pelvis for childbirth, circulates throughout the body and loosens ligaments in the feet. This systemic ligament laxity, combined with the extra weight of pregnancy, often causes the arch to drop and the foot to lengthen or widen. For many women, these structural changes are permanent.
Furthermore, the protective cushioning on the sole of the foot changes with age. These specialized fat pads, located under the heel and ball of the foot, can thin out and redistribute over time, a condition known as fat pad atrophy. This thinning reduces the foot’s natural shock absorption, causing it to spread out more when weight is applied. This gradual process affects the foot’s overall shape and how a shoe fits.
Practical Steps for Addressing Adult Foot Changes
Since foot dimensions can change in adulthood, it is advisable to have both feet measured regularly, even when replacing old shoes. Foot size can change in both length and width, and one foot is often slightly larger than the other. Taking a measurement ensures that new footwear accommodates the current size and shape of your feet.
When purchasing shoes, focus on comfort and support over previous sizing habits, recognizing that your current size may be different from the one you wore in your twenties. Look for footwear that offers a wider toe box and adequate arch support to help manage arch flattening. Supportive shoes or orthotics can help properly distribute pressure and provide cushioning where natural fat pads have thinned.
If you notice sudden, significant changes in foot size, or if the change is accompanied by persistent pain, swelling, or new foot deformities, consult a podiatrist. A professional can assess the structural changes, address any underlying medical conditions, and recommend appropriate interventions, such as custom orthotics or specific exercises. Addressing these changes proactively helps maintain mobility and reduces the risk of further foot problems.