Does your skin get thicker or thinner as you age?
Your skin thins at two levels with age: that is well established. Retinoid creams have the most support if you want to slow that process; discuss stronger variants (such as tretinoin) with your doctor or dermatologist.
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.
Based on two review studies (Michigan), a meta-analysis of 133 studies, several additional reviews, a small biopsy study (n=71), an RCT on strength training (n=56), and an RCT on chemical peeling (n=46). The evidence for the general direction (thinning skin) is solid; for the interventions it is moderate to limited.
Does your body odour change as you get older?
Yes, your body odour changes noticeably with age: from your forties onwards your skin produces a compound that adds a greasy, grassy note, and at the same time you become less able to perceive smells yourself.
Does your skin age faster than your organs?
It has not been proven that skin as an organ naturally ages faster than your internal organs, but it is more vulnerable to sun and other external stimuli that measurably raise biological age. Limiting UV exposure is the best-supported way to slow skin ageing.
Does sleep deprivation age your skin faster?
Studies show that sleep deprivation damages the skin barrier, reduces the production of skin-strengthening proteins, and slows DNA repair in the skin. Getting consistently good sleep is therefore one of the most tangible things you can do for your skin.
Does menopause accelerate skin ageing?
Menopause noticeably accelerates the loss of collagen, moisture retention and skin thickness, but spots and skin cancer are almost certainly caused by sunlight. If you are experiencing skin complaints around menopause, discuss with your doctor whether HRT makes sense for you as an overall package.
Does chronically poor air quality age your skin?
Chronic exposure to air pollution measurably accelerates skin ageing, and the evidence for this is reasonably consistent. If you live or work in a structurally polluted environment, paying extra attention to your skin barrier (a good moisturiser, sun protection) is a worthwhile step.
Does a low-fat diet slow skin ageing or make it worse?
A low-fat diet is not necessarily better for your skin: the type of fat counts more than the amount, and monounsaturated fats and omega-3 may actually be beneficial for skin elasticity. Base your choices on the type of fat in your diet, not on total fat restriction.