All about energy balance & how it dictates weight change


When I speak to individuals and we start to discuss nutrition, it quickly becomes apparent that they know about all the different types of diets from fasting, ketogenic, low fat, atkins etc.; but what they can’t grasp is how these diets (from a body composition perspective i.e. fat loss/muscle gain) really work at the fundamental level; whilst some diets try to reduce our eating window to make us more anabolic (lol), or avoid a particular macronutrient because the creator feels that this macronutrient is making us fat i.e. carbohydrate commonly (double lols), there is one overriding factor that dictates weight change.


What all (good) nutritional protocols have in place at the very base level of their composition, is a manipulation of our energy balance to place us in an environment to either create or get rid of tissues of our body (usually create new muscle and get rid of stored fat). This is going to be the topic of this discussion and understanding that every single effective nutritional strategy will have this at its core will liberate you into actually picking a ‘diet’ based on sustainability and personal preference, I would even go as far as to say it’s no longer a diet, just nutritional principles based on your goals and preferences.


Note: I will preface this article by saying that there will be no references present in this as this is a fundamental concept of human biology, it is not up for discussion and is concretely consolidated in what is 99% the truth, open any human biology educational text and there should be some discussion on this confirming all that will be included.



‘What is energy balance?’


Energy balance is the relationship that exists within the human body and the environment, that determines the difference between energy being placed into the system & energy that is put out of the system and into our environment. This may sound very wordy, but is basically our physical outputs of energy in the form of work, heat etc. vs. inputs of energy in the form of nutrition. The relationship between these inputs and outputs (and energy in general) is subject to the law of thermodynamics, this law basically states that energy is never truly created or destroyed, it exists within us and around us, it is simply transferred between these entities.


Again, sorry if this is a bit wordy for some, when energy is input (via nutrition) it must do something within the body, or be released by the body (in the form of heat for the most case). When energy is input it is either utilised in the body to perform work (in the form of physical activity or maintenance/function of our internal systems like the digestive system, cardiovascular system etc.), be stored for later use (either as fat tissue, in the blood or glucose stored within the liver & muscles generally) or released from the body as heat, as a result of work performed by the body, to allow us to maintain thermoneutral if temperatures are high (thermoneutral is the resting temperature of the body, it will differ depending what our external environment entails.)


The human measure of energy intake is calories (kcal), of which all foods are composed of (YES CALORIES MATTER, THEY ARE NOT A MYTH); a kcal is the unit of energy that is needed to take 1 litre of water, up 1 degree Celsius (not exactly useful by itself but I love useless information).


Our energy balance is constantly in flux, we don’t just stop and start it each day, week or month; any state of energy balance is always temporary; whenever we eat, we are in a positive/surplus of energy balance (more on this further in) until we use this energy, once we have used it we then go into a negative state/deficit of energy balance as we still need to maintain bodily functions and create movement. This is important to understand, this is why there are no good/bad foods, why when we eat out at the weekend with our families, that we have not ‘ruined’ our diet; we just have to understand what happens as a result of these things, what we are more interested in is which state of energy balance we are in the most often, we need to be in a specific energy balance (that is concordant with our goals of weight gain/loss) more often over a period of time to have that desired effect; if we over eat, we can easily reduce our energy intake a little over the next few days to compensate, if we under eat we can do the same in the opposite fashion. Whilst I don’t recommend the two scenarios I just described, life happens sometimes, and spiralling out of control is common place, understanding how we can manipulate variables based on what has happened to re align our energy balance to our goals, we are always in control and we can always get ‘back on track’, don’t stress life’s little occurrences.


‘What is Metabolism?’


People talk a lot about their metabolism, metabolic rate and any plethora of interchangeable phrases including the word, yet it is often misunderstood. Metabolism is the sum of all of the chemical reactions that occur within the body, from scratching your eye, to digesting your last meal, to freeing up energy to allow you to effectively dash for that bus you are about to miss; anything that happens within your body is a component of metabolism.


Metabolic rate is the energy cost of all of these chemical processes within the body, commonly measured in kcals; we can separate human metabolism into 4 pretty distinct categories; resting metabolic rate, non-exercise activity thermogenesis, thermic effect of feeding and thermic effect of exercise.


Resting metabolic rate is the energy expended due to maintenance of our internal functions and current bodyweight, it is commonly measured in a metabolic chamber in a lying/still position, by measuring oxygen consumption and using fancy calculations based on bodyweight and other anthropometric measures, and in healthy humans is pretty consistently similar between humans when matching for bodyweight (this is important, people seem to think that they have a slow/fast/whatever metabolism because of their genetics or some other reason, but for 95% of individuals this is not the case, other components of human metabolism effect how well we ‘burn’ energy).


Non-exercise activity thermogenesis (NEAT) is the energy demand on our body created by all our involuntary and unconscious movement (i.e. walking from our desk to the toilet, fidgeting, washing the pots etc.). This is not included within thermic effect of exercise which is voluntarily done (although it is sometimes hard to wrap your head around as walking is for the most part, a chosen task, but for the sakes of simplicity it is separated into NEAT). To measure NEAT (accurately) we would need a monitor of someone’s heart rate, oxygen consumptions and body measures to calculate it in kcals, this is not really realistic for anyone other than the most advanced athlete; so as walking comprises the biggest chunk of NEAT, using a step counter/fitness tracker is a good way to get a good estimate (whilst some are more accurate than others) of NEAT expenditure if you consistently use the measure, and will give us a baseline measurement that we can use to increase or decrease energy demand from.


NEAT is the most diverse characteristic of metabolism between humans, it is what is mainly attributed to these ‘metabolic adaptations’ that almost every person claims to be suffering from, when in reality it is due to poor monitoring/utilization of nutrition and exercise that has caused a chronic reduction in NEAT, making them more lethargic, unmotivated to move and less likely to engage in conversation than if they supplied the energy they really needed (I commonly take on new clients, get them to eat more than they have ever eaten before and they start to lose weight, I attribute this to NEAT with more motivation to physically move and train creating more need for energy).


Thermic effect of feeding is the energy demand derived from consuming and digesting the food we intake, thermic effect of feeding is around 8-12% of our total caloric intake, so this needs to be accounted for within metabolism, the more/less you eat will determine how many calories you ‘burn’ through the process of consuming and utilising them. Eating more frequently does not increase the energy costs of digesting the food, so the myth of ‘stoking your metabolism’ by eating more often is just that, a myth, thermic effect of feeding is the same regardless of the amount of meals you eat (although there is a slight higher energy demand for utilizing proteins but when protein is equated for bodyweight this is a moot point); it is important to note that I’m not dismissing meal frequency as not influencing the outcome for body composition change, it may have some benefits in the rate of synthesising proteins, refilling glucose stores etc. but it does not by itself increase the energy demands for digesting our food.


Thermic effect of exercise is the energy demand derived from the resources needed to fuel our voluntary exercise. All exercise has energy demand from strength training to endurance training, you will generally find that the lower volume (amount of work) that a training style utilizes, the lower the energy demands are per session. A lot of trainers talk about high intensity interval training (HIIT) and exercise post oxygen consumption elevations (EPOC); high intensity interval training is maximal outputs of effort (usually on a bike, treadmill, rower etc.) done for short durations (10 seconds up to about 60 seconds) with short rest intervals in between bouts; EPOC is the extra demand needed on the system for oxygen after doing such an energy type, because the exercise is anaerobic in nature (this means that fuel is derived without the presence of oxygen), oxygen is at high demand when you stop. Whilst there is some truth in this, the benefits are very insignificant, in a real world situation we may get a 5% extra caloric burn over slower, steady state exercise. My problem with this is that the ratio of fatigue:energy burn from HIIT is pretty poor, there is only a small benefit for extra caloric burn, but the extra energy burned comes at a huge cost for fatigue, preventing the amount of resistance training volume we can perform effectively, resistance training is the crucial (if not the most important) variable in maintaining muscle mass on a diet and increasing muscle mass during a gaining phase, so we have to make sure we weigh up these variables before implementing cardio to alter our energy balance.


‘States of energy balance’


A state of positive energy balance would be a situation in which our energy inputs equal more than our outputs, as we discussed, this is always a temporary state and will change once this extra energy is utilized; we need to be in this state of energy balance more often than not over a period of time to gain weight, being in this state of energy balance guarantees weight gain. A state of negative energy balance would be a case in which our energy inputs equal less than our outputs, this state of energy balance would guarantee weight loss; when we maintain this state we start to use the bodies stored energy (body fat, stored glucose etc.) to meet energy demands, if we are not resistance training our body will also very quickly breakdown our lean muscle tissue for energy. When stored energy is not readily available or easily accessible, the mechanisms that maintain our homeostasis (maintain a constant internal environment) will start to shut down non vital human functions to reduce energy demands, this is to get back to that homeostatic state; these changes can include reduction in movement (as we discussed with NEAT), reduced digestion, even reproductive function & more; this can start to happen very quickly if we also enter too large an negative energy deficit, this is just more of an emergency response of the body to maintain homeostasis.


When we transition from a state of negative to positive energy balance, these ‘metabolic adaptations’ start to reverse, as long as the state is maintained for long enough; this is a benefit (and necessity) for someone that has been dieting for any decent period of time. When we maintain a state of positive energy balance for too long or too excessive a magnitude of positive energy balance, we can start to see some negative effects, we can start to see storage of fat tissue once our stores of glucose are ‘full’, we see this more so if we don’t provide a stimulus to turn any of this energy into anything productive (energy for movement or to create tissue such as muscle). Some other side effects of chronic positive energy balance can include fat stored in the blood, this can start to create a block in our circulatory system, which can be the startings of various metabolic diseases such as diabetes, cardiovascular disease etc. if not managed.


‘Energy balance for fat loss/muscle gain’


By now we understand that to lose weight, we need to maintain periods of negative energy balance, and to gain weight we need to maintain periods of positive energy balance; whilst this is always the case and will not change, when we look at improving body composition we need to consider some other variables.


The inclusion of a high protein diet and performance of resistance training for improving body composition is important; if we do not take advantage of these two, when we enter a state of negative energy balance we will still lose weight, but this weight will come from as much lean muscle tissue as body fat, lean muscle tissue is liberated for energy very readily in the absence of a stimulus (external input) to give it a reason to stay. In the case of positive energy balance, with the absence of resistance training and a high protein diet, the majority (if not all) of weight gained will go to storage (of glycogen and body fat).


When we implement a high protein (1.8-2.2g per kg lean body weight) & progressive resistance training we bias more of our weight gain to be comprised of new muscle tissue (still not all of it but significantly more) and more of our weight loss to come from stored fat with more retention of lean muscle tissue.


‘Energy balance over time’


We briefly touched on this before but the longer we remain in a state of either positive or negative energy balance, the more our internal environments starts to change to slow down weigh gain/loss, these ‘metabolic adaptations’ come in the form of fatigue or increased motivation to move, decrease in function of non-vital (and eventually vital) bodily functions, decrease in sensitivity to nutrients, increased levels of hunger and more. We will eventually come to a point where it is not feasible to continue with our current energy state in any sort of productive fashion; it is important that after a period of time, we give ourselves a ‘break’ from one or the other, and spend time in neutral/maintenance of energy balance.


This allows a lot of the adaptations that take place to start to reverse, so then when we resume our previous goal, we can be productive in doing so with less resistance from the body, we can do periods of these working & breaks to allow us to eventually get to near anywhere we want (realistically) in terms of leanness (not so much in muscular gains as there is a certain rate at which we can gain muscle based on several factors). The law of diminishing returns states that the more we apply a stimulus/do something, the less of a result we get each time, this is very relevant for manipulations of energy balance. This is vital in understanding why we may have hit a plateau, we may need to take a break away and then resume on when we are back to baseline; if you can understand and utilise this concept you will be well on your way to your leanest & most muscular physique (or whatever physique you desire).


Aaron Brown