If you ever look at a young person you will see how soft their skin is, how plump it is and how it recovers from each move and every gesture, how unblemished and how perfect the features. Clean, bouncy and as inviting as a hotel bed with new duvet and freshly ironed sheets. Plump is the right word – all the tissues supporting the skin are firm and healthy; the fatty layer, the blood vessels, the supporting collagen fibres and the "ground substance", the hydrating gel.

Youth is wasted on the young, or so they say. Slowly and imperceptibly the supporting layer starts to lose its fullness. Like an apple drying in the fruit bowl the skin starts to sag, to line and pucker, eventually overhanging its bony margins at the jaw line and in the cheeks. In the absence of severe weight loss or other accelerating elements (smoking, sun exposure, extreme illness) volume loss precedes loss of elasticity by about seven years.

Most lines on the face are caused by the underlying loss of volume. Look at the face of somebody overweight – they have few (if any) lines and their face is still round and plump. Up till recently we used to fill the lines themselves, but now this new understanding has allowed us to replace the underlying volume disturbance and achieve better, more natural and longer lasting results.

Some lines still need filling, or the individual may desire a fast-fix in the short term -  cheek lines, nose to mouth lines and lips, for example. These areas are subject to constant movement and micro-trauma in the skin. The newest generation of flexible hyaluronic acid fillers suits these areas very well by minimising the micro-trauma to the skin-filler interface.  Fillers such as Esthelis (marketed as Belotero in the UK) are the flexible fillers that we use for these particular areas. Cheek lines, crows feet, forehead lines, lipstick lines, lines on the chest/décolleté all respond well to fine flexible fillers.