Understanding Total Daily Energy Expenditure

Total Daily Energy Expenditure explained

The human body just like all material objects is subject to the laws of physics. The composition of the human body is primarily dictated by nutrient partitioning and energy. When we consume calories in food or drink we are inputting energy into a biological body which prefers to stay in homeostasis. Energy specifically is what is represented as calories on the nutrition label and it is this energy which ultimately forms our total energy balance. This balance can be represented as a ratio between energy in and energy out.

[ - 10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 ]

If we look at it like a number line then we can see that when we spend more energy by being more active our daily energy expenditure rises. This means we disrupt our daily energy balance if we move more, consume more oxygen, and do more work. If we think of the heart as having some finite number of heart beats over a lifetime and if we know each heart beat costs energy then typically there are estimated to be between 2 to 4 billion heart beats over a life time.

Human beings have hearts which become more efficient with training so that the resting heart rate slows down over time as fitness improves. This means less heart beats are necessary to spread oxygen throughout the body as a person becomes more oxygen efficient (aerobically fit). Human beings also if food is properly labeled can control our energy balance by manipulating the two variables under our control.

Variable 1 Calorie input

This represents how much energy we input into our organism or organic system. This can be controlled by measuring the units of energy for everything we consume and budgeting our consumption rationally and consciously. According to medical science we know that human health can be measured by blood tests primarily with scans as secondary. A blood test result which shows signs of chronic inflammation in the form of hsCRP is a clear sign that something is wrong. A blood test result which shows elevated LDL, elevated A1C, are two additional examples where the body is sending a signal that something is wrong. Blood testing is essentially our best known signalling mechanism by which the body communicates it's health status to the interpreter.

Nutrition density when kept high on a per calorie basis is thought to be associated with good health. It is in essence a type of efficient consumption of calories and calorie restriction is heavily associated with longer lifespan in mammals. Because calorie input is a variable which a human can consciously and rationally control it is imperative that the understand of this be taught to all people of age to feed themselves.

Variable 2 Calorie output

This variable is energy expenditure. In specific total energy expenditure is the total amount of energy output in terms of calories used per day. So if you are very active then determined by your genetics you will burn through a specific amount of calories at a burn rate which is measurable. An average person burns calories at a rate of around 1 calorie per second (60 calories per minute) just at rest. Some burn quite a bit more than this as genetically determined and some burn a bit less but this is a typical average. If we do 60*24 we will reach around 1440 calories in a day which represents the "Resting Energy Expenditure". This is also called the resting metabolic rate which is the amount of calories you'd burn in a coma. This level of energy expenditure represents the absolute minimum required to keep your body functioning at all and anything less than this amount results in an energy deficit.

Total daily energy expenditure factors in your activity level which means it takes REE and adds activity to the equation. This addition of activity to REE produces TDEE or total daily energy expenditure. The more active you are on a particular day the more energy you need to remain in daily energy balance. If you shift your ratio too far to the left then your balance goes into the negative energy balance resulting in weight loss. The more extreme -10 means you'll lose weight at the maximum rate but it also means your body will catabolise without any regard to long term health or fitness (muscle loss).

The body goes into either anabolic state (growth) or catabolic state (deconstruction). When the body is in the deconstruction state it first will tap fat cells for stored energy. These fat cells essentially get filled up and they drain as the body is in a negative energy balance. A typical rate of drainage if at a healthy rate is around 2lbs a week or less. If the human being consumes a greater amount of calories than their body requires for maintaining energy balance that day then the excess goes to fill up the fat cells. In essence the overdose of calories over a long period of time results in obesity and being in a long term deficit of calories results in starvation. It typically takes months to become obese and it typically takes month to starve but genetics play a major role in how fast it takes. Generally it can be calculated and estimated how long a person can be in a reduced calorie state or in an abundance of calories.

• TDEE is the Total Daily Energy Expenditure. Become more active and TDEE goes up and be less active for it to go down.
• REE is Resting Energy Expenditure and it is genetically determined. The more efficient your body is at spending calories the lower REE will be.
• Obesity is the overdose of calorie intake over a long period of time resulting in disrupted energy balance and full fat cells.
• Starvation is the under intake of calories representing a negative energy balance until eventually the heart does not have enough energy to continue to beat.
• The two variables which every mammal has to control body composition is energy in and energy out representing the influence on the TDEE.
• The body signals it's health status in various ways but blood testing is among the most accurate we can measure. If blood work returns a result which says something must change then heed the warning sign if you wish to maintain homeostasis.

References

1. Energy Expenditure and Energy Balance: Collection of 300+ Studies
2. Total Daily Energy Expenditure