Menstrual cycle The first period usually begins between twelve and fifteen years of age, a point in time known as menarche. They may occasionally start as early as eight, and this onset may still be normal. The average age of the first period is generally later in the developing world and earlier in developed world. The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women and 21 to 35 days in adults (an average of 28 days). Menstruation stops occurring after menopause which usually occurs
Menstrual cycle trait preferences do not occur throughout the cycle. Females have been found to experience different eating habits at different stages of their menstrual cycle, with food intake being higher during the luteal phase than the follicular phase. Food intake increases by approximately 10% during the luteal phase compared to the follicular phase. Various studies have shown that during the luteal phase woman consume more carbohydrates, proteins and fats and that 24-hour energy expenditure shows increases between 2.5-11.5%. The increasing intake during the luteal phase may be related to higher preferences for sweet and fatty foods, which occurs naturally and is