What is TDEE? It’s Total Daily Energy Expenditure. It’s an estimate of your average daily energy use from resting metabolism, digestion, activity and exercise.
Knowing your TDEE is extra useful if you want to lose fat or gain muscle!
That’s because fat loss is achieved by creating a deficit (eating below your TDEE). On the other hand muscle gain is optimised by creating a surplus (eating above your TDEE). Eating equal to your needs is often called ‘maintenance’, because it helps your weight stay steady.
So how do you work out your own energy expenditure?
The only reliable method (outside of laboratory testing) is to track your food intake for a few weeks while your weight is stable. The fast way is to use an online calculator, but if you do just be sure to remember all calculators are rough guesses at best.
Rather than build my own inaccurate TDEE calculator I’ve created five charts that will help you think this through properly. The data I’ve used is doubly labelled water measurements for 645 adults aged 20-70 years from the Institute of Medicine’s from the Dietary Reference Intakes.
Still with me? Great! Now for the fun stuff!!! Here’s 5 facts about TDEE that should be common knowledge. As you work through the graphs make sure to try and plot where you think you might be.
1. Men have higher TDEE
In general men have higher energy needs than women. Some of this is down to men being bigger, and more active, but even at the same weight men tend to have higher energy needs due to their larger organs and lower fat percentages.
Here are some simplified averages for men and women.
Energy needs can be broken down between your resting metabolism (liver, brain, muscles . . ), digestion, general activity and formal exercise. Resting metabolism is on average good for 60% of the total.
These numbers may look a little higher than the figures you commonly hear (2,000 for women, 2,500 for men). That’s because they are based on actual data of real people instead of ‘healthy weight’ ideals.
Now, let’s talk about age.
2.Young people have higher TDEE
As people get older their energy needs tend to decline.
Explaining this phenomenon is not straight forward. Some of it is lost muscle mass, some changing lifestyle and some seems to be things changing at a cellular level too.
Whatever the reason is you can see it clearly in the data.
The first thing to note is the enormous variation. The second is the clear decline in energy needs with age.
Average needs for women drop from 2,700 calories at age 20 down towards 2,000 at age 70. While for men they begin way up near 3,400 at 20 and fall to 2,800 by 70 (which seems surprisingly high). For the geeks the R² suggests that age explains more of the decline among women than men.
Next up is weight!
3.Heavy people have higher TDEE
Heavier people generally have higher metabolic rates. This reflects the fact that more energy is required to move a larger body and that larger people often have bigger muscles and organs (resulting in higher resting metabolisms).
Here’s how the data looks for weight:
In this graph you can see that even for the same weight men typically have an energy expenditure that is 500 calories higher than women.
Light women who clock in around 50kg (110lbs) average just 2,200 whereas a 100kg (220lbs) woman could expect to use 2,800. The effect of weight on energy needs is even greater in men. With 100kg (220lbs) men regularly clocking in around 3,500 calories a day it’s little wonder big men often drop weight the fastest.
It’s again important to stress the huge variation. Note the poor women in the bottom right hand corner, who maintains over 110kg (240lbs) off just over 2,000 calories. That’s a maintenance of just 8 kcal/lbs!!
Let’s talk about height.
4.Tall people have higher TDEE
When it comes to losing weight, or keeping weight off, tall people have it good. Tall people burn more energy than shorter people, so they can afford to eat more while maintaining weight and have more energy to play with when cutting. Part of this is simply having more surface area to dissipate heat.
Here’s how the data looks.
Virtually all the women with slower metabolisms (below 2,000) are shorter than 170cm (5’7). And below 160cm (5’3) a third of the women have energy needs below 2,000 calories.
In the black dots for men you can see that the bulk of the high energy users (above 4,000) are up around the six foot mark. You can see from the R² that height is explaining around 10-15% of the variation.
Last up is activity level.
5.Active people have higher TDEE
The primary reason you should never trust a TDEE calculator, or any weight loss calculator for that matter, has to do with their simplistic treatment of activity level.
Almost all calculators estimate your resting metabolism (which already has a degree of variability ±20%), and then multiply it by an activity multiplier based on exercise levels (typically 1.2, 1.375, 1.55, 1.725, 1.9).
Getting these multipliers right is very hard. And pretending they are determined largely by exercise is plain false. They are a complex function of genetics, work life, exercise patterns, muscle mass, postural control, propensity to fidget . . .
Here’s what the correlation looks like between TDEE and activity level.
Activity level is a stronger explainer of TDEE than age, weight or height. In this data set it explains 40-50% of the variation.
If you’ve ever known one of those people that just doesn’t seem to put weight on regardless of what they eat you’ll probably find they are a world class fidgeter. Other things that drive up activity levels are physically active jobs (think labourer) and endurance training (think triathlete).
People with low activity levels (below 1.5) are likely to combine desk jobs, limited exercise and low spontaneous activity (fidgeting, posture control, shivering . . ).
What is Your Total Daily Energy Expenditure?
When it comes to weight loss, weight gain or maintenance, the proof is in your pudding! You need to let your results dictate your calories. There are two main reasons for this.
Firstly, calorie calculators are terrible. They take a number with ±20% error and multiply it by a activity factor that is at best an educated guess. Any calculation can easily be out by ±500 calories. Enough to make or break a diet. I find body-weight multipliers a less misleading starting point, because they don’t pretend to be accurate.
Secondly, your energy needs are not static. They change over time and are particularly affected by diet. In studies where people are overfed energy needs increase, and in dieting studies they decline. A couple of months of bulking can easily push your TDEE up by 500 calories, while a few months of cutting will likely drag it down by 500.
This is why the leanest people in the world don’t use calculators. They track their energy intake and adjust based on results. So if what you’re doing isn’t working . . . . change it. Try to eat as many calories as you can while losing 0.5-1.0% of your weight per week, but don’t be surprised if you have to dig deep in order to get lean.
Lastly, don’t make the mistake of assuming you are ‘average’. In the 645 data-points in this sample I couldn’t find a single women using exactly 2,000 calories a day, nor a man that needed 2,500.
Your energy needs are unique and they will vary over time!
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