BMI (Body Mass Index) and BMR (Basal Metabolic Rate)

BMR or Basal Metabolic Rate (metabolism) is the number of calories the body burns per day at rest. Your BMR is the energy expended by the body at rest to maintain normal bodily functions. This continual work makes up about 60-70% of the calories we use (“burn” or expend) and includes the beating of our heart, respiration, and the maintenance of body temperature. Your BMR is influenced by a number of factors, including age, weight, height, gender, environmental temperature, dieting, and exercise habits. Because of the increased activity of cells undergoing division, the younger the person, the higher (faster) the metabolism. And the taller and heavier a person is, the faster their metabolism. Because of the greater percentage of lean muscle tissue in the male body, men generally have a 10-15% faster BMR than women. And when you go on restrictive, traditional diets, your BMR can drop by as much as 20%. People living in tropical or very cold environments generally have BMR’s 5-20% higher than those living in more temperate climates. In general, depending on the intensity and duration, consistent exercise can also increase your BMR.
In addition, knowing your body fat percentage is critical when trying to improve your body composition. For example, if you have 25 kg in fat and 75 kg in lean body weight, then your total body weight is 100 kg. If you lose 1 kg in fat and gain 2 kg in muscle, now you weigh 101 kg. By using a regular scale, you might think you gained fat. So, by calculating your BMI or Body Mass Index, you will know how much of your fat to lose and how much muscle to gain to be in ‘normal’ range. BMI can also be used with body composition to assess lean body weight, or muscle mass. Lean body weight is low if BMI is low and body fat is high. Alternatively, lean body weight is high if BMI is high and body fat is low.