basal metabolic rate
Basal Metabolic Rate
Basal metabolic rate is the amount of energy required by the body to maintain normal function during the rest. If the rate is high, then more calories are burnt while at rest. Read on to know more about this.
- Genetics: Some people are born with a higher metabolism rate, while some have slow metabolism.
- Age: BMR generally decreases with age. After the age of 20 years, it reduces about 2% every decade.
- Gender: Men have a lower body fat percentage and a greater muscle mass. As a result, they have a higher BMR.
- Body Surface Area: Your height and weight contribute a lot in determining your BMR. The greater is your body surface area, the higher is your BMR. Thus, thin and tall people have a higher BMR.
- Weight: If your body weight is more, then your BMR would be higher. The metabolic rate of obese women is about 25% higher than the metabolic rate of slim women.
- Body Fat Percentage: If the body fat percentage is lower, then the BMR will be higher. Generally, men have a lower body fat percentage, and hence they have 10-15% higher BMR than women.
- Body Temperature: With an increase of 0.5°C in the internal body temperature, BMR increases by about 7%. The chemical reactions in the body take place more quickly at higher temperatures.
- Diet: Because of starvation or serious abrupt calorie reduction, BMR can drop by about 30%. The low-calorie weight loss diets can cause dropping of BMR to up to 20%.
- External Temperature: External temperature also affects the BMR. Exposure to low temperature leads to an increase in the BMR in order to maintain body's internal temperature.
- Glands: Thyroxine accelerates the metabolic activity of the body. More the thyroxine produced, higher is the BMR. In case of thyrotoxicosis (excess production of thyroxin), BMR may be doubled.
- Exercise: Physical exercise decreases body weight by burning calories as well as increases BMR by building extra lean tissue.
- Quick Method Based on Total Body Weight: It is a quick and easy method to determine the calorie requirements. It involves the use of total current body weight times a multiplier. Fat loss = 12-13 calories per lb of body weight Maintenance (TDEE) = 15-16 calories per lb of body weight Weight gain = 18-19 calories per lb of body weight This method doesn't consider the activity levels or body consumption. The extremely active people may need much more calories than this formula indicates.
- Equations Based on BMR: Determine the basal metabolic rate using various factors such as age, weight, height, and sex is more accurate method to calculate TDEE. Then, multiply the BMR by an activity factor to calculate TDEE.
- The Harris-Benedict Formula: This is a calorie formula using factors such as age, sex, weight, and height to determine the BMR. The lean body mass is not taken into consideration in this method. Men: BMR = 66 + (13.7 x wt in kg) + (5 x ht in cm) - (6.8 x age in years) Women: BMR = 655 + (9.6 x wt in kg) + (1.8 x ht in cm) - (4.7 x age in years)