Lose weight: Creating a calorie deficit that results in weight loss is hard work. Most recommendations say that to lose weight, you must exercise for at least an hour a day, five times a week. The type of exercise matters, too.
Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia. hair shaft. the nongrowing portion of a hair that protrudes from the skin, that is, from the follicle. hair shaft. The keratinized portion of a hair that extends from a hair follicle beyond the surface of the epidermis.
The hair shaft is made of a hard protein called keratin and is made in three layers. This protein is actually dead, so the hair that you see is not a living structure. The inner layer is the medulla. The second layer is the cortex and the outer layer is the cuticle.