What is BMI, BMR, and TDEE

As you are digging more information about weight loss, and how to do it safely and healthily, you will at some point stumble upon these: BMI, BMR, and TDEE, amongst other confusing jargon. But if you are just starting, in my personal opinion, these three is what to look out first.

BMI (Body Mass Index)

Many health practitioners use this a way to decide whether you are on a healthy weight. You can calculate it manually by dividing your weight in kg by your height in meters squared. I heard that you can do it in imperial measurement, but I like metrics and found metric system usually more accurate. Anyway… you can always use BMI calculator anyway.

THIS is the one from NHS, UK.

Now, how are you using this data to decide whether you are within the healthy weight?

Generally you are considered as underweight if your BMI is under 18.5kg/m2, and overweight if you are above 25kg/m2, and obese if it’s above 29kg/m2. Anything in between 18.5 – 25kg/m2 is considered as a healthy BMI.

NHS admitted that BMI has its limitation. It doesn’t count for other factors such as muscle mass (body builder is significantly heavier but have a very lean muscle), ethnicity (Asians have higher proportions of body fat, so the overweight BMI actually started at 23, instead of 25), gender, etc.

Some people have ditched this BMI concept, or try to ditch it because it is considered as an archaic way of measurement, but I have to say that until today it is still relevant for general public. If you are a sports person, you generally don’t need this anyway because you have millions of way and experts to take care of your fitness level and health. But if you are just an average people, BMI and its flaws is still one of the best approach to measure your health.

healthy weight chart
image source NHS

BMR (Basal Metabolic Rate)

You need energy to live. Generally we associate energy/calorie with activities like walking, running, carrying baby up and down the stairs while carrying three bags of groceries at the same time. However we rarely realise that we also need energy to keep our body to function well.

If we translate Basal Metabolic Rate to easier words to understand, it means the basic energy rate of changing food into energy.

The other way to explain it is that if you are bed bound, and unconscious, your BMR number shows the amount of energy your body needs to keep you alive, and your organs to function properly.

image source pexels

The million dollar question is how are you going to use this data to aid your weight loss program? Depends on the situation some people can eat below their BMR safely. People who are doing intermittent fasting has gone below BMR regularly, and it serves them very well with their weight loss. 

However generally, BMR is used alongside TDEE to decide how much your calorie allowance is.

TDEE (Total Daily Energy Expenditure)

Almost self explanatory really. Basically BMR+ the approximation of the energy you will need for your daily activities. Imagine a twin with exactly same height and weight, and body fat percentage. One is a chef, who’s working all day on their feet, and the other is a banker, who’s working sitting down. The chef will have a higher TDEE based on his job.

But that’s not all, the chef drives to work, but the banker bike to work. Now the banker has a higher TDEE because of his daily cycling. Everybody’s TDEE is different based on their activity level, means more active people can basically eat more too.

image source pexels

The rule of thumb is that you can lose weight safely and healthily if you are consuming calories above your BMR but below your TDEE. That is the simplistic way to approach it, but that is the easiest way to explain. If you are eating more than your TDEE your extra calorie is then going to be stored in your body as that extra kilo. This… works for people who wants to gain weight too.

How do you know your BMR and TDEE? There are plenty sources that provides calculator, but my favourite is this.

If you’re just started and not sure how to decide your own calorie allowance, MyFitnessPal can calculate it for you and suggest the safe calorie goal for you too.

Hope that helps, and good luck with that goal jeans…




Asian BMI — https://www.runsociety.com/bmi-calculator/

NHS BMI — https://www.nhs.uk/live-well/healthy-weight/bmi-calculator/

BMR/TDEE calculator — https://www.sailrabbit.com/bmr/


2 thoughts on “What is BMI, BMR, and TDEE

Leave a Reply