Bigger Waists: Are They Unavoidable with Age?

In February 2022, the Journal of Biological and Clinical Anthropology published research about a newly appreciated fact in human morphology. Long after our other bones quit getting larger, our hip bones continue.(1)  

In 2012, we reported a new study demonstrating that hip bones continue to grow with age. By age 20, most people have achieved their maximum height. But researchers at the University of North Carolina at Chapel Hill School of Medicine found that while people don’t grow taller after age 20, they do grow wider—well into their 70s. On average, the pelvic width of the oldest people in the study was nearly 2.5 cm larger than the youngest patients. This increase in pelvic diameter could lead to an approximately 7.6 cm increase in waist size from age 20 to age 79, regardless of body fat increases.

In the current study, Lukas Waltenberger and colleagues dived into the why of age-related pelvic widening. Can we avoid it? The answer is largely “no.” They studied 167 skeletons with known age and cause of death. Waltenberger et al. find that some of the pelvic widening is attributed to hormone-related changes, especially during childbearing years in women. However, both men and women experience a gradual widening of the pelvic bones throughout life. They also hypothesize that much of the widening is remodeling. For one, it may be a response to how bones weaken with age, keeping the pelvis prepared for the substantial pressures it endures. Similarly, the remodeling may also simply be a response to those same lifelong pressures. In sports, the pelvis may be called to withstand pressures that are eight times a person’s body weight.

Maintaining lean muscle mass, orthopedic ability, and cardiovascular fitness is important for wellbeing and quality of life. That being said, now we can give ourselves a little bit of a break from the blame and guilt from increasing belt sizes.

Reference

1. Waltenberger L, Rebay-Salisbury K, Mitteroecker P. Age dependent changes in pelvic shape during adulthood. J. Biol. Clin. Anthropol. 2022; 79(2): 143-156.