Posh moisturisers make a lot of scientific claims how they work, but they all have the same basic principle
Skin is made up of 3 layers, and we are taking about the top one here, as this prevents water loss form the deeper areas of skin. Normally this is about 15% water – when is gets less than this our skin feels dry and flaky. The cells in this layer contain substances that usually prevent this from happening, but some materials – such as detergents and solvents – can wash these away
A moisturiser is basically just a way of putter water back into this layer, and keeping it there – usually by using something called a humectant. This is then blended with some kind of fat or oil to create a nice cream.
Good question cheese2000; i don’t know but there’s an assumption there that it does! The cynic in me, would like to have a look at the data, the funding of the research, and whether any of the “effect” could be attributed to a placebo! Knowledge about science can be useful at times on a daily basis – especially if you’ve the choice between paying £3 or £12 for a moisturising cream!