Moisturizers accomplish their tasks in one of two ways: by absorbing or delivering moisture. Let's take a closer look at the two types of ingredients that perform these functions.
Humectants are ingredients that retain moisture, and they're found in lots of cosmetics. Even toothpaste has humectants in order to retain moisture and prevent the decomposition of the toothpaste in the tube. In body cleansers, humectants include glycerol, glycerin and vegetable oil based substances.
Humectants in body cleansers absorb water from two different places: from within and from without. This means that humectants can draw water up from the dermis to the epidermis, as well as absorb moisture from the air itself. This is why glycerin soaps form beads of water when left exposed to the air.
Emollients soften skin in part by delivering the goods directly -- as in, the composition of the product itself will moisturize your skin, as opposed to attracting water to your skin like a humectant would. They also help retain moisture by coating your skin, giving it increased protection from external irritants and trapping the moisture within. Emollients used in skin care products include carrier oil, urea and man-made substances such as silicone oils and isopropyl myristate
If you're trying out different body cleansers without any success, see if those products tend to fall in one category or the other. Now switch. While people with dry skin may be better off using emollients, those with oily skin may benefit more from the ability of humectants to keep pores from clogging.