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Why your RMR is like a low bridge

The amount of energy you burn each day, in calories, is known as your TDEE – your total daily energy expenditure.

It’s the sum of how many calories you burn at rest (known as your RMR) plus the number of calories you burn doing your daily activities, digesting food and other bodily functions when you’re not resting.

For you to maintain your weight and not increase body fat, your energy expenditure (TDEE) should be matched by the energy in the food and drink you consume. That number of calories that keeps your weight the same is known as your ‘maintenance calories’.

Therefore, your maintenance calories and your TDEE are two very important numbers because, knowing them means you can work out what you can eat in order to lose body fat, maintain weight or gain muscle.

But they are just numbers. Or, rather, they are estimates or calculations of numbers. You DO NOT need to obsess over them and you don’t even need to know them, especially if your main goal is to lose body fat. Why? Because at the end of the day your body weight will show pretty conclusively if you are hitting your maintenance calories.

​​Consider this analogy, where your height is your maintenance calories and a bridge you walk under is your TDEE.

If you have been measured as 5’7″ tall but bang your head every time you walk under the bridge that declares a clearance of 5’9″ there is no point in re-measuring either the bridge or yourself – you are too tall for it! To walk under the bridge you need to duck down (reduce your calories), whatever the sign on the bridge (your calculated TDEE) says.

Forget about the numbers. Getting under the bridge is an empirical exercise. Either your height or the bridge clearance – or both – has been calculated incorrectly. You can’t change the height of the bridge but you can duck.

You need to consume less if you want to walk under the bridge!

​In the same vein, if you are putting on fat, you are eating more than your maintenance calories, regardless of whatever any formula or machine says it is or however many calories you think you are consuming every day (or how active you think you are). You need to reduce calorie intake until you stop putting on weight, and then duck down some more (go into a calorie deficit) so you start losing weight.

Many people come to Bodyscan wanting an accurate measure of their RMR and maintenance calories because “I’m eating less than maintenance and I’m still not losing weight.” Well, if you’re not losing weight you are definitely NOT eating less than maintenance! Rather than try to make RMR/maintenance fit consumption, you need to change consumption to fit your TDEE!

If people see an increase in body fat fat when they “are in a calorie deficit” it’s because, pure and simple, they are NOT in a calorie deficit! This is because

a) they are eating more than they think they are
b) they are less active than they think they are
c) both of the above

Tracking calories is notoriously difficult and unreliable; on average people underreport their calorie intake by about 47% and over-reporting energy expenditure by about 50%.

It may well be easier to track what you currently eat and adjust from there.

A DEXA scan at Bodyscan

When you book a DEXA scan with us, the post-scan consultation will use your body composition results in our calculator to give you a very good idea of your resting metabolic rate. Our team will use their expertise to gauge your actual activity level (usually lower than you think yourself!) and therefore your maintenance calories. From there we will suggest a sustainable calorie deficit for fat loss or an optimum surplus for muscle gain. However, if we follow the ‘moral’ of the low bridge analogy, the numbers we give you for maintenance (the height of the bridge), the height of the bus (your total calorie target) and the gap between bus and bridge (your deficit) are just numbers. If you don’t lose weight (fat) then ignore the numbers and consume less until you do!

To track your progress over time you can save a lot of money by purchasing an annual pre-paid package (all DEXA scan costs on our pricing page). The packages give you credits to book your scans at any time over the course of a year. The optimum frequency for scans is every 12-16 weeks, to keep you accountable and to ensure that what you’re doing is actually working – you want to lose fat, not weight; and gain muscle, not fat!

If you have any questions, write to us here; and read our Google reviews to see why we’re rated five stars!

Philip Chant
Director