When describing the gradual decline of one's health or vitality, there are a number of synonyms for the phrase "wastes away". These include terms such as withering, dwindling, deteriorating, declining, and fading. Each of these terms conveys a sense of gradual loss or decline, and may be used in different contexts depending on the situation being described. For example, withering might be used to describe the gradual decay of a once-beautiful flower, while dwindling might be used to describe the gradual depletion of natural resources or energy reserves. Ultimately, the choice of synonym will depend on the desired tone and context of the writing or conversation in question.