The aging of skin has been associated with an increase in size of the adipocytes located within the subcutaneous tissue. This topic is the subject of our study conducted on rats clinically treated with L-acetyl-carnitine (LAC) at 4, 8, 16, and 21 months of age and on a control group. Normal rats showed a significant increase in adipocyte diameter between four and eight months, and between sixteen and twenty-one months of age. Rats treated with L-acetyl-carnitine did not show significant changes up to the age of sixteen months, but did so between sixteen and twenty-one months of age. Four-month-old rats, both those under treatment and controls, did not show a significant change in adipocyte diameter. On the other hand, rats receiving L-acetyl-carnitine showed significantly smaller adipocyte diameters than those of the control group. Our results demonstrate that the long-term administration of L-acetyl-carnitine blocks the progressive increase in size of the subcutaneous adipocytes present in the rat's aging skin. We hypothesize that L-acetyl-carnitine reequilibrates the catabolic deficit of fats in the skin of the elderly.