One of the side effects of ageing is that the levels of hyaluronic acid and collagen in our skin deplete. As a result, our skin becomes less smooth and plump and we lose volume in our faces. The underlying structures that support our skin also degrade and gravity takes it's toll, causing the fat in our faces to "slide" and/or break down. This makes our cheeks less full and elevated and causes lines known as nasolabial folds or nose to mouth lines to form and jowls to appear.
Volume loss can be caused by a number of factors from sun damage, the natural ageing process to dramatic weight loss, stress and illness or drug use. You may also hear volume loss referred to as "lipoatrophy" or "facial wasting". This generally refers to localised volume loss related to illnesses such as diabetes and multiple sclerosis and the use of certain medications to treat them, which leave the suffer looking gaunt. People with HIV also suffer from extreme loss of volume in the face as a result of the illness. This is known as "HIV-associated lipodystrophy".
The term volume loss is generally used when talking about loss of fat in the face.
Anyone can get facial volume loss but as it is mainly associated with ageing it tends to be more common in people from their 30s upwards.