Does your skin get thicker or thinner as you age?

Your skin consists of two layers: the outer epidermis and the deeper dermis (the supportive tissue). Both become thinner as you age. The epidermis loses cells because the number of skin stem cells declines. The dermis loses its firmness as skin cells age and produce progressively less collagen. At the same time, those ageing cells release inflammatory substances that actively break down the skin's structure. This is not mere theory: a meta-analysis of 133 studies across 37 body locations confirms that the epidermis consistently thins with age.

There is one smaller biopsy study (71 people) that found no significant relationship between age and epidermal thickness. That study clearly stands alone against a considerably larger body of evidence pointing in the opposite direction. Worth noting, however, is that the study did find that men have a thicker epidermis than women, and that smoking was associated with a thinner stratum corneum.

The functional consequences are noticeable: the skin barrier works less effectively, wounds heal more slowly, and the risk of skin cancer increases. These are direct consequences of the structural changes in both skin layers.

The thinning can be partly slowed or even reversed. Daily creams containing retinoids (a group of vitamin A derivatives, available both over the counter and on prescription) can thicken the skin in both layers and reduce fine lines. A chemical peel showed a measurable increase in epidermal thickness in a small study of postmenopausal women. And a small Japanese RCT in sedentary middle-aged women found that strength training made the dermis thicker, while endurance training did not. It should be noted that three researchers involved in that strength training study had ties to a cosmetics company, so treat that result with some caution.