It seems that every time we open a fitness magazine there is a new miracle fat loss diet, the 5:2, the Paleo, the Dukan and so on. But what is it that really drives fat loss? In this article, we have a look at what energy balance is and why we need to understand it for fat loss. N.B. this article refers to weight loss in healthy individuals with no underlying health issues. Witten by Liam Darville.

You see all successful diets have one thing in common – they create a caloric deficit. In basic terms, they manipulate the energy balance equation to ensure that you consume less calories than you expend, which in turn leads to weight loss.

Energy intake = energy expenditure + change in body stores (Energy balance equation)

So where does the confusion occur?

It comes through a lack of understanding as to what energy balance is and ultimately to create an energy imbalance we must first understand what energy balance is.

So what is it?

Energy expenditure has 4 components: 1) Basal Metabolic Rate (BMR) – the energy required to perform basic bodily functions. 2) Non-Exercise Activity Thermogenesis (NEAT) – every movement we do that is not pre-determined exercise (think walking to the fridge, standing up, nervous twitches, etc). 3) Exercise Activity Thermogenesis (EAT) – the energy used in exercise i.e. going to the gym, for a run, etc. 4) Thermic Effect of food (TEF) – the energy used in the digestion of food. These 4 components make up your Total Daily Energy Expenditure or TDEE. If we consume and expend equal calories then we will be in a state of equilibrium and weight will be stable (energy balance).

Therefore if we wish to lose weight then an imbalance must be produced causing the body to utilise energy from means other than those through consumed calories i.e. our fat stores. Equally in weight gain a diet must ensure that we are consuming more calories than we expend. And it is this that all successful diets will initially address.

However what many so called fad diets fail to acknowledge or even consider is that energy balance is not a fixed entity and so a one size fits all approach will never work. The body is a highly adaptive organism changing to meet the demands that are placed upon it. As it is exposed to stresses it will become more efficient thus lowering the energy cost of exercise, in addition as weight is lost all movements will necessarily require less energy, reducing daily energy requirement accordingly. Furthermore during a prolonged calorie deficit your body will sub-consciously move less, gesticulate less, fidget less and get up and move about less than before in an effort to conserve body stores attempting to adapt to a lowered energy availability. Energy balance consequently must be considered a dynamic entity and so any diet that is utilised must also be dynamic, adjustments made to either energy expenditure or energy intake to maintain a calorie deficit and prolong weight loss.

Is that all there is to it?

Essentially yes. For weight loss that is a very basic summation of what needs to be considered, however most of us are looking for FAT loss and although the principles remain the same there are few further things to consider when pursuing fat loss with concurrent maintenance of muscle mass.

1)     Adequate protein must be consumed. Depending on your activity levels this should be > There is little evidence to suggest anything > has any added benefit though.

2)     Exercise in addition to a caloric deficit will aid maximal maintenance of muscle mass. Heavy compound exercises are currently considered optimal for muscle maintenance.

3)     Sufficient sleep >6hrs.

How will I know if my diet is effective?

In a nut shell you will lose weight. There are times where you may well be fortunate enough to lose fat and gain muscle at the same time, generally when you are just beginning training or are returning from a long absence or an injury. There are of course exceptions to every rule and some people will experience the holy grail of training and gain muscle and lose fat at the same time but it is rare! In general the scales (used routinely so that weight is taken at as close to the same state as possible), body circumferences and progress pictures are an easy way to track the success of any diet (unless you’re fortunate to have access to a bod pod or DEXA scanner). Once you have a grasp of this the one thing that all diets MUST consider is whether the diet is sustainable, if you cannot adhere to your diet then you will never maintain any gains made (flexibility is the key here but that is for another day).

So onto the next article and the logical step from energy balance is to look at the most misunderstood aspect of training and diet – the humble calorie.


Take Home Points:

·       Energy balance is a dynamic and thus must be re-evaluated regularly to maintain weight loss or gain.

·       In HEALTHY individuals caloric deficit and sustainability of diet are key.

·       During fat loss adequate protein intake > and exercise are essential to maintenance of muscle mass

·       Conscious movement i.e. going for a walk during a caloric deficit may aid fat loss.



Hall, KD, Heynsfield, SB, Kemnitz, JW, Klein, S, Schoeller, DA and Speakman, JR (2012) Energy balance and its components: implications for body weight control. The American Journal of Clinical Nutrition, 95, pp. 989-994.

Hill, JO, Wyatt, HR and Peters, JC (2012) Energy balance and obesity. PMC Circulation, 126(1), pp.126-132.

Hill, JO, Wyatt, HR and Peters, JC (2013) The importance of energy balance. US Endocrinology, pp. 27-31.

Manore, MM (2015) Rethinking energy balance. ACSM Health and Fitness Journal, 19(5), pp.9-15.

Saris, WHM (2003) Sugars, energy metabolism and body weight control. The American Journal of Clinical Nutrition, 78, pp. 850-587.

Schoeller, DA (2009) The energy balance equation: looking back and looking forward are two very different views. Nutrition Reviews, 67(5), pp. 249-254.

Trexler, ET, Smith-Ryan, AE and Norton, LE (2014) Metabolic adaptation to weight loss: implications for the athlete. Journal of the International Society of Sports Nutrition, 11(7), pp. 1-7.



Getting down to business with the very best supplements and food, TPW™ Nutritionist has an incredible amount of knowledge on all things sports nutrition. With a Masters in Sports nutrition, some say TPW™ Nutritionist is a bit of a know it all, but we love that!

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