Many assume that products designed to hydrate deeply actually do. It's a bit more complicated. Skin is a barrier, and the same properties that keep irritants out also keep most of what you apply on top from getting where the aging actually happens. Knowing that difference means thinking about skincare in a whole new way. 

Your skin is comprised of two primary layers: the outer layer, epidermis, and the inner layer, dermis. Anything you put on your skin, regardless of how much you spend or what the ingredient list is, resides in the outermost portion of the epidermis - the thinnest layer of the epidermis, at that - known as the stratum corneum.  There's a scientific reason for that. The 500-Dalton rule, a well-known theory in dermatology, declares that anything above a certain molecular weight is simply too large to move through the skin and into the lower layer, hence directly impacting the dermis.  Hyaluronic acid, for example, is renowned as one of the most powerful hydration actives because it can hold up to 1,000 times its weight in water. However, its molecular weight is generally above that 500-Dalton threshold, meaning it remains on the surface in the epidermis - not the dermis. 

Many people confuse a couple of categories of professional treatment that, by all rights, should be reasonably distinct. Traditional dermal fillers add volume to a specific area - whether they're done properly and ethically and with the right product, they're meant to often restore lost structure in a defined area of the face. They are not, in general, meant to improve overall skin quality or texture. They fill, generally, a shape.  Bio-remodelling is a very different beast. Rather than adding volume to a spot, it involves the injection of a very structurally stable and slightly modified form of hyaluronic acid in a highly concentrated form. It is smoothed through the tissues rather than sitting in a clump, with the idea being to hijack the skin's own fibroblast response to begin producing collagen and elastin of its own accord. Of course, everyone wants to claim new collagen growth - but bio-remodelling is one of the few that has been rigorously demonstrated to do this, in the case of at least of four different types of collagen, as well as elastin - which is one of the ways in which it is distinct from the traditional filler camp. This is where the concept of a professional Skin Treatment becomes relevant - not as a substitute for a home routine, but as the foundation layer beneath it. Once the dermis has adequate hydration and fibroblast activity is stimulated, surface products have a healthier structural environment to support. 

The dermis is the location where both collagen and elastin are synthesized and where they are maintained. Collagen and elastin provide the structural matrix that makes the skin firm as well as its ability to rebound after being pulled away from the body and returned. These long-lived proteins are made from amino acids, water, and energy supplied by the mitochondria of fibroblasts - cells whose job it is to produce proteins. Unfortunately, fibroblast production of collagen and elastin slows significantly with age, and that slowdown, coupled with the gradual degradation of the skin's pro-elastin remodeling machinery, results in a deficit that leads to lax skin. The body can no longer bounce back as it used to when it was younger. Glycosaminoglycans are water-binding molecules that occur naturally in the dermis and also serve to help support the extracellular matrix as well as maintain the structure around both collagen and elastin. As the dermis dries out, some of the most significant structural components of the skin begin to lose their support. 

Healthy, well-hydrated skin at the dermal level has a different appearance than skin that has been hydrated topically. It feels different - less crepey and smoother. The way light bounces off of it is different. It is often referred to as a "glow," but it's less about glowing and more about light being reflected off an even surface because your extracellular matrix is in good condition and your collagen network is intact and functioning. There's no serum that can replicate that because there's no serum that can get anywhere near the tissue that is responsible for that. You will age. Fibroblast activity still slows down. There will still be less hyaluronic acid in your skin. But your extrinsic factors - like UV exposure and pollution - will be accelerating the process on the surface, which is just going to compound the issues you already have going on underneath. Professional treatments address the intrinsic side. Your home care routine should be focused on the extrinsic factors. These are not competing strategies. They're approaching the problem from different reaches. 

It's likely not the products themselves that are frustrating to spend money on while not seeing results, but rather that they cannot solve a deep problem. If the dermis is deficient, nothing you put on the epidermis will be able to fix it. Bio-remodelling improves the dermis and creates a better environment to support the epidermis. After that, you keep up maintenance (instead of trying to grab on to something your epidermis can't get hold of) and provide support at home.