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Basal Metabolic Rate

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The Basal Metabolic Rate is essentially a measure of the required amount of energy needed to maintain bodily function while at rest. The most significant requirements that BMR energy needs meet are in processes such as establishing and maintaining a normal breathing pattern, heartbeat, blood circulation and temperature. The primary factors influencing BMR include age, gender, muscle composition, hormonal levels, exercise levels and many more. It is important to recognize that an individual’s BMR is not static and many of the above factors can affect the utilization of energy either positively or negatively. For example, men on average have higher BMRs when compared to women simply due to an increased amount of muscle mass. While it may seem …show more content…

These changes are typically brought on by hormonal fluxes that control the different phases of the cycle in order to ovulate a mature oocyte. The average menstrual cycle is 28 days in length and progresses through four distinct phases, each with its own regulatory hormone. The phases and their associated days are as follows: menstruation, or the early follicular phase (days 1–4), late follicular phase (days 5–11), periovulation (days 12–15) and the luteal phase (days 16–28). 1 The major hormonal secretion sites are the hypothalamus, which secretes gonadotropin-releasing hormone (GnRH), the pituitary, which secretes follicle-stimulating hormone (FSH) and luteinizing hormone (LH), and the ovaries, which secrete estrogens and progesterone. Of the three types of estrogen involved in the menstrual cycle, estradiol, estrone and estriol, estradiol is considered the most potent and is known as E1.2 In lieu of discussing the many hormonal fluctuations of a typical menstrual cycle, a diagram has been included to display the oscillations of the hormones described …show more content…

It was found that energy expenditure correlated to the fluctuations in E1 and progesterone in that there was a significantly lower energy expenditure during a 24-hour measurement during the follicular phase when compared to the menstrual (~3.8%) and luteal (~4.9%) phases.12 Interestingly, this study also found that expenditure while asleep was significantly greater during the luteal phase than during the menstrual and follicular phases which is a direct correlation to an increase in progesterone. As a result of this study, it was concluded that fluctuations of hormones throughout the menstrual cycle significantly affects energy expenditure, notably during sleep, but also in overall BMR.12 This can be linked directly to fluctuations in progesterone and can be observed when measuring energy expenditure and BMR over a 24-hour

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