What is Body Mass Index [BMI]?
Body mass index, [BMI], is a measure of body size, combining a person’s weight with their height to assess if their weight is healthy.
How do I calculate my body mass index [BMI]?
Body mass index is worked out by dividing an adult’s weight in kilograms by their height in meters squared. FX-Sport provide a simple BMI calculator as well as a height to waist calculation for a better indication of healthy weight.
Is body mass index [BMI] accurate in 2019?
BMI gives a basic indication as to whether you are carrying too much weight. However many now believe it is no longer a good indication of healthy weight. This is because it does not take body composition into consideration.
What are the limitations of Body Mass Index [BMI]?
Your BMI may be an indicator that you are carrying too much weight, but it cannot indicate body composition, ie the difference between excess fat, muscle or bone. It also does not take into account age or gender.
This means therefore that muscular adults and athletes may be categorized as “overweight” or “obese” even though their body fat is low. Also, adults who lose muscle as they get older may fall into the “healthy weight” range even though they may be carrying excess fat.
Can I get a better indication of healthy weight than BMI?
Yes. Using skin calipers, hydrostatic weighing [or underwater displacement weighing] and measuring waist circumference are three alternative methods. Hydrostatic weighing is considered the most accurate. It compares a patient’s normal body weight outside of the water to their bodyweight while completely submerged to estimate body composition. However, measuring waist circumference is a very useful [and the easiest] indicator of healthy weight. Put simply, waist circumference in inches should be half or less than half of your height in inches [see below].
Does my waist size matter for a healthy weight?
Yes. Measuring your waist is a good way to check if you are carrying too much fat around your stomach. Too much fat in this area can raise your risk of heart disease, type 2 diabetes, stroke, gall bladder disease, sleep apnea and osteoarthritis. You can have a healthy BMI but still have excess fat around your stomach. This can indicate you could still be at risk of developing these conditions.
What is Basal Metabolic Rate [BMR]?
Basal Metabolic Rate is the minimum amount of energy your body requires on a daily basis, to carry out your body’s essential chemical processes, whilst at rest. Also know more generally as your natural metabolism, BMR involves all the chemical processes that go on continuously inside your body to keep you alive. This includes keeping your organs functioning normally, breathing, repairing cells and digesting food, all whilst at rest.
Why is Basal Metabolic Rate [BMR] important to know?
Once you know your BMR calorific value, you can then calculate your Total Daily Energy Expenditure [TDEE].
What is Total Daily Energy Expenditure [TDEE]?
This takes into account your weekly activity levels. It is the total number of calories you should consume per day to maintain your weight, taking into account exercise levels. It is your Basal Metabolic Rate multiplied by an “activity multiplier”, the value of which is determined by how much exercise you perform per week. A TDEE calculator is shown here:
Total Daily Energy Expenditure [TDEE] Calorie Calculator:
So what is the best way to lose weight?
The calculators above show how to simply calculate your Body Mass Index [BMI] and your Basal Metabolic Rate [BMR] in calories, to then calculate your Total Daily Energy Expenditure in calories [TDEE]. Your TDEE includes your weekly activity/exercise levels. You will then have a target number of daily calories to consume less than to lose weight. To best lose weight, this would be combined with more or harder exercise.
So consume fewer daily calories than your TDEE and exercise more or harder.