Total Daily Energy Expenditure
"what is TDEE? and why is NEAT important"
If you are unfamiliar with these acronyms (.fitness is full of them) dont worry we shall uncover what they are shortly.
NEAT = non exercise adaptive (activity) thermogenesis. TDEE = total daily energy expenditure. We'll get down to what they are soon enough. Both these factors contribute to the calculations we make when designing fat loss or muscle building based nutritional plans, well any nutritional plan in fact. To understand them we must understand metabolic rate and all that contributes to it. What is metabolic rate? It's quite simply the amount of units of energy used by an animal per unit of time. You might also have heard of BMR; BMR (Basal metabolic rate)
Basal meaning: essential for maintaining the fundamental vital activities of an organism.
in essence fundamental. BMR (Basal metabolic rate) is the amount of energy per unit of time that a person needs to keep the body functioning at rest. Sometimes referred to as coma calories. BMR is the first thing we coaches aim to estimate (without a lab we can only estimate) as it gives us the baseline clue as to how much energy you need per day. Why is this important? Quite simply every organism on planet earth kind of works in a similar way. We all require energy to sustain life, if we don't get that energy we eventually die. In between sustain and die there is obviously a big gulf, like get abs or build muscle or lift 200kilos. The same laws of physics apply to everything from a pan of boiling water, your car to our complex biological system. This being the laws of Thermodynamics. We, as living systems are privy to the first law of thermodynamics just like any other living organism.
The 1st law states:
that heat is a form of energy, and thermodynamic processes are therefore subject to the principle of the conservation of energy.
This means that heat energy cannot be created or destroyed. It can, however, be transferred from one location to another and converted to and from other forms of energy.
This law basically describes how the human body metabolises and transforms food energy (calories) into heat energy to be used, or if not needed, stored as fat.
Trivia: scientists use a bomb calorimeter to measure the energy value of food.
"Snowflakes, we are not!"
We are nothing special, If we want to lose weight (by weight i mean fat) we have to obey the same principles as your overfed cat or dog. The whole thing boils down to energy balance. In humans we measure energy in Calories. A Calorie is the energy needed to raise the temperature of 1 gram of water through 1 °C Scientists use that bomb calorimeter to then measure how many calories macronutrients and foods contain. which is cool because now we know;
Humans use energy
Food contains energy
Humans eat food to extract energy
thermodynamic law states if we don't get enough energy we lose mass.
So if we can estimate how much energy you need each day to sustain your current mass. And we can estimate how much energy you consume, we can deliberately alter the balance of energy in vs out to elicit a response. We can be in 3 states of energy;
Isocaloric: this is equilibrium, balanced energy in vs out. weight stays the same.
Hypercaloric: consuming more energy than is currently being used. weight is gained.
Hypocaloric: using more energy than is being consumed. weight is lost.
We fly between these states constantly depending how fed or not or active or not we are. If we sit at two of those states for long enough, (Hyper/hypo) noticeable changes to mass begin to occur. So yes changes in mass always come back down to calories in vs out. There is obviously a lot of nuance here and what those calories are comprised of does have an impact but it doesn't alter energy in vs out. That is rule 1. Which brings is back around to our metabolic rate. When you first come in to see me and express the desire to change body mass/shape/size/weight etc one of the first things we'll discuss is food intake. And one of the first things I'll do is begin to try and estimate how much energy you need on a day to day basis, this is known as your TDEE or total daily energy expenditure (remember). The energy you burn daily comes from 3 main areas; note; You might want a calculator as this will lead into the realms of setting calorie levels for different goals. So you'll never need me again! Also I’ll be hurling around three and four letter acronyms like ninja stars shortly so watch your head. Total Daily Energy Expenditure (TDEE) is generally thought to me made up from 3 different components.
BMR. basal or resting metabolic rate (RMR) - 75%
TEF: the thermic effect of food. 10%
TEA: the thermic effect of activity.
Let's look at each a little deeper.
1.BMR... well just to be annoying what we actually measure is RMR ("resting" metabolic rate) which is the state rested before eating, basically not asleep (it measures between 5 and 15% higher than bmr because you're awake) Sorry to be a stickler.
RMR makes up around 60 to 75% of your daily energy expenditure and is the energy associated with the maintenance of major body functions
everything from the beating of your heart to protein synthesis, literally everything that is running in the background whilst being awake but not active contributes to RMR.
This part is largely determined by your LBM (Lean body mass)
(lean body mass = total body weight minus fat mass. leaving behind all the other bits and bobs like muscle, organs, brain etc.)
Basically, the higher your lean body mass the higher your RMR as muscle tissue etc does require a slightly higher amount of energy than fat as it ticks over, not much but a bit.
muscle mass costs approx upto 25% of daily calorie expenditure.
organs cost approx upto 60% of daily calorie expenditure.
(note; yes you can get a slightly better estimate of RMR if you figure your LBM, but total body weight usually does just fine, the only time i use LBM is in very overweight individuals.)
Other factors that affect RMR;
Gender - women tend to be on average 5% lower than men, due in part to differences in LBM and fat mass but also hormones.
Age - decreases of LBM and slower bodily functions.
here is a very simplistic, but perfectly viable estimation to gauge your RMR.
Body weight in lbs x 10 = RMR
2. TEA - No, don't go and stick the kettle on just yet
This component includes energy expenditure due to physical work, muscular activity, including shivering and fidgeting, as well as physical labour and exercise.
This is where it gets tricky, for me that is.
TEA is the most variable component of daily energy expenditure and can constitute 15 to 30% of energy expenditure daily.
This accounts for all activity over the basal level.
Now that is wildly variable person to person, ALL activity,
leaning over to the copier at your desk
going and putting the kettle on
taking the dog for a walk
going to the gym
yes even shivering and fidgeting.
where other components of TDEE are predictable, this is the part of the equation that is the hardest to measure, as this difference can range from 10 to 100% over baseline levels depending on the individual,
this is why we like to get a detailed picture of your day to day work life style, activity, training etc
Two people of identical build can have massively different energy needs just because of the different effect of activity eating up energy (or not).
To counter this we must make as close estimation as we can.
We do this by multiplying your RMR by an activity factor;
LIFESTYLE & TRAINING FREQUENCY ACTIVITY MULTIPLIER
Sedentary plus 3-6 days of weight lifting 1.3 – 1.5
Lightly active plus 3-6 days of weight lifting 1.5 – 1.6
Active plus 3-6 days of weight lifting 1.7 – 2
Very active plus 3-6 days of weight lifting 1.9 – 2.2
This is also why i use an "Observe phase" . We simply have to start with an estimate first and make changes as we go based on what rate those changes in weight/fat are occurring. A period of time where we just get going and pay attention provides a lot of information that an equation cant.
Body weight in lbs x 10 x activity factor = TDEE
3. TEF - Thermic effect of food also known as DIT (Dietary induced thermogenesis)
TEF is the cumulative increase in energy expenditure after several meals and constitutes approximately 10% of daily energy expenditure
This is the amount of energy it costs you to extract that energy from your food.
This is like the administration cost of processing nutrients in the following way.
Protein - gets broken down and processed by the liver. and also has the highest admin cost. 20-30% of the macronutrients caloric value is lost in simply processing, one reason why high protein diets are so successful for fat loss.
Carbs, yes all carbs, regardless if it's donuts or brown rice eventually get broken down to glucose, the administration cost is only about 5-6% of the cals.
Fats - need almost no admin work to be stored.
while all thats interesting it's also a bit futile to try and figure all that out, so we simply say TEF costs around 10% of total daily caloric intake.
if you consume 2500 calories it will cost you approximately 250 cals simply processing it, that is its "thermic effect".
The 4th (other) factor - the adaptive component
NEAT Non-exercise Adaptive Thermogenesis.
This technically sits under the TEA umbrella, but NEAT is as unique as it is unpredictable.
It refers to all that subconscious stuff like fidgeting and shuffling instead of sitting still, general moving about, even stuff like tapping your toes on the floor or those annoying people who have to bounce their knee up and down on the chair next to you! Or tapping fingers on the desk and just any number of other strange quirks we do that burns off calories with absolutely no useful reason.
This component is so variable person to person and is also hard to quantify, most people have no idea it's happening, the difference NEAT makes form person to person can be quite large ranging from a mere 200 cals per day up to 900 cals maybe more of total caloric expenditure per day!
This can explain, those people who just never seem to put on weight, they might simply just run higher than you, you know those people, walk everywhere, never sit still, always fidgeting, talk a lot etc
It also explains why during periods of excessive calories some people don't really change whereas others seem to put on fat just looking at a pizza.
the excess calories seem to really jump up some peoples NEAT to large degree to the point where they are just burning lots of useless energy per day via foot tapping and doing extra steps without it even registering.
And yet In others, NEAT remains low despite all those extra cals and fat gain happens.
Ever been on a really active holiday or a city break with loads of walking, ate loads and drank like a fish, only to return home home expecting to crush the scales only to see little to no change?
All that extra energy usage is a bit like NEAT, your baseline energy output has just ramped up, this can make a big difference, which is why a lot of walking especially if you work at a desk job is sooooo helpful.
This also goes the other way, and leads us to the dieting paradox;
When you lose weight, RMR goes down, Some of this is simply due to reduced body weight (a smaller body burns less calories) but there is also an adaptive component due to changes in hormones like leptin, insulin, nervous system output and thyroid hormones .this lessens the actual deficit that is being created because the previously estimated maintenance value is no longer correct (to keep losing fat at anywhere near the same rate, calories have to be reduced further to take this reduction into account). basically when we diet our bodies internally recognise the lull in energy and down regulate to save on fuel which is obviously a very useful evolutionary tactic to stay alive longer during periods of famine, but this adaptiveness happens to people to greater degree than others. So when dieting, NEAT in particular reduces - in some to a larger degree than others, which explains a little why some lose at faster rates than others despite similar deficits etc. with all that it's important to note that all the above does not create a static one size fits all equation, it's in flux dependant on what the individual is consuming (mainly total energy intake) and what they are doing (exercise/activity) and what environment they are in.
Hence why this is not an exact science, constant monitoring and adjusting will be required. so yes, try a bit of tracking, stick to some calories and watch what happens, don't rush, nothing bad will happen.
There you have it, a "short" breakdown of what your daily energy requirements are made of.
I know it was long, but it goes to show that getting energy balance right matters, not just eating less and less.
your requirement for energy is as unique as you are, simply why a packaged diet is a guessing game.
Now you understand in greater detail that changes in overall body mass boils down to long-term energy balance of energy in from food and energy out via your Total Daily Energy Expenditure as calculated by all those components above.
You may never need any of that info but it's good to know