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. The cortex makes up the majority of the hair shaft.