Energy balance

Energy balance.  A concept that cannot be denied by anyone as the fundamental underpinning concept of weight loss (as much as ‘experts’ of fad diets, low-carb zealots, and those with some other bullsh*t products to promote would love to argue against). It doesn’t matter whether you’re on 10g of carbs, 100g carbs or even 1000g carbs. If you are in an energy deficit you will lose weight. It doesn’t matter if you drink every disgusting laxative tea on the market, a bucket load of coffee (FYI adrenal fatigue isn’t a real thing), have hormonal issues that potentially influence your metabolic rate, or eat 3 mars bars a day. An energy deficit means weight loss, regardless of macronutrient intake.

Lots of us meticulously track one side of this energy balance equation. We follow structured meal plans or use apps such as My Fitness Pal to obsess over grams of protein, carbs, fats and fibre. We know (within the standard margin of error of our foods), how much energy we consume on a daily basis. But what about the other side of the equation? How many of us have any real idea of our energy expenditure?

There are 3 major components of energy expenditure: basal metabolic rate (the amount of energy that we need to perform basic body functions); physical activity and the thermogenic effect of food (energy required to break down and metabolise food). Although BMR contributes the highest proportion of our energy expenditure (and is largely a function of our body mass), physical activity is the easiest for us to control and contributes 20-30% of our expenditure in a healthy active individual. So why is it so ignored by people looking to lose fat, when they are so obsessed with the calories they consume and the training that they do inside the gym? If you think about it, a 60 minute resistance training session may burn approximately 300 kcal (if you push it hard), but if we average a daily expenditure of say 2500 kcal, why would we not focus more on that latter 88% rather than solely on the 12% that takes place inside the gym?

We all know those people: drive to the gym, lift, drive home, spend the rest of the day in the office sat at a desk. We also know these people who appear to do no exercise, eat lots of food, and remain relatively slim and/or lean. We know those who seem to be able to eat so much more food than others despite appearing to have similar body compositions. But what we miss from the initial judgements we make of these people, is their physical activity, their non-exercise activity thermogenesis (NEAT – the energy expended on everything else we do that is no training, sleeping or eating). It is far easier to use energy walking to and from work, being in an active job, walking the dogs, than it is to use energy to fuel a 60 minute resistance training session.

Lot’s of you will have seen the memes – “People think [the gym] is the challenge, but it is the other 23 hours of the day that require the most dedication”. As much as the motivational meme can give me the heeby jeebies, there is some truth in this one!


FitBits – the coolest watch since Baby G (those over the age of 30, you know)

In the last few years, we have seen the release of a surge of commercially available activity trackers. It’s no longer the odd exercise addict at work that has this plastic strap permanently attached to their wrist, but individuals of all ages, genders and physical activity levels. We brag about our hours of sleep, fight to lower our resting heart rate and compete with friends to get the highest step count for the week (or is that just me and my loser social company…?). For those yet to be sucked in to the craze, FitBit’s basically track your daily step count, in addition to monitoring your heart rate, sleep patterns and any exercise that you do. You can tell your FitBit that you’re doing weight training, cross-trainer, running, whatever it may be, and based on your heart rate and movement, it provides an estimation of your energy expenditure i.e. your calorie burn, for that exercise session, in addition to providing a daily energy expenditure for the full 24 hours of that day.

What can the FitBit tell us about fat loss? As we know, our energy balance is the determinant of fat loss. We can track our energy intake using apps like My Fitness Pal (no, this is not solely for the purpose of seeing if we can get that slice of pizza in to our macros), and this allows us to ensure that we are not going over our set energy intake. The FitBit allows us to do similar for our energy expenditure. Just like apps for what we eat, this can be prone to error, but in general, consistently gives us an indication of whether or not we are active enough to reach our goals of fat loss (or, whether we are consuming sufficient calories to reach our goals of muscle gain if we are super active individuals).


Dieting and your energy expenditure

It has been well-documented in research, that during a negative energy balance (i.e. when you’ve been dieting for a while [not Monday – Friday until the weekend, a real while]), you tend to get less active. That’s right, we have some sort of compensation mechanism inside us that tells us to conserve energy. So when dieting for a prolonged period of time, we tend to inadvertently get a little lazier. We may fidget less, walk less, move less. This is one of the reasons why after prolonged dieting, sometimes our progress can plateau.

This isn’t the only reason that our expenditure can decrease with dieting duration. Most of us (I’d hope), when aiming to lose body fat, will likely increase exercise and/or decrease energy intake. If you are relatively new to exercise, you will find that you will utilise a fair amount of energy to perform a given exercise of a certain intensity and duration e.g. a 5km run. However, as your experience of doing this increases, you will become more efficient at doing this same run, and because of this increased efficiency, your body will require less energy to do the same task. It’s one of those times that ‘efficiency’ isn’t necessarily our best friend (the ONE time boys, ONE, we like efficiency the rest of the time please so keep trying…).

So, if we think about those of us who are undertaking a prolonged state of dieting and in a constant state of energy deficit, due to a reduced physical activity and increased efficiency of exercise, our total daily energy expenditure is likely to inadvertently decrease. This is not what we want for fat loss. Cue the help of an expenditure tracker to monitor this for us…


FitBits – just how accurate are they?

Recently, FitBits were compared against the research- grade accelerometers for the measurement of energy expenditure (Chowdhury et al., 2017). Energy expenditure over 24 hours was compared between research-grade device, the FitBit, Apple Watch and Microsoft Band. The Apple Watch came out on top as the most comparable to the research-grade device in both a 24 hour period and also in simulated daily activity settings, followed closely by the FitBit. In general, the FitBit slightly underestimated energy expenditure as compared to the research-standard by approximately 400 kcal/day. If we think about this in terms of applicability to fat loss, I’d say it’s better to think that our energy expenditure is lower than it is (i.e. we push ourselves therefore to do more), rather than higher. So although it underestimated expenditure in this case, thinking that we are expending less than we are may serve as some sort of negative reinforcement to move more. In addition, there’s something to be said for methods of measurement that are ‘consistently inconsistent’. There is a margin of error in many measurement techniques that we use, and indeed this study suggested that none of the devices were suitably similar to the reference method of measurement. But how many people are willing or able to access research-grade devices (in this case the Actiheart accelerometer and indirect calorimetry [the type breath analysis you always see on those channel 4 diet shows]). In my opinion, provided that we are aware of the potential inaccuracies, and that the margin of error isn’t vastly higher on one day compared to the next, commercially available activity monitors can provide a useful gauge of physical activity levels to work with, specifically in relation to setting fat loss and muscle hypertrophy goals.


Setting your energy expenditure goals

So, you’ve got your FitBit, you’ve been hitting your 10,000 steps daily for a while now (the little watch celebration never gets old, personalised electronic fireworks anyone?), and now you want to start tracking your training efficiently with the help of your new best friend. But where do you start? Truth be told, it can be a little stab in the dark when it comes to setting target energy expenditures if you don’t want to start racking your brain for Standard Grade Maths (GCSE for all you English folk). You also have a choice to aim for a target exercise energy expenditure (the calories you burn during exercise and training) vs. total daily energy expenditure (the calories you burn over a 24 hour period). So where to start?

  1. Establish your current goals: fat loss, muscle gain, maintenance.
  2. Track your current training energy expenditure for the next 7 days. Start your FitBit when you start your training, and stop when you’re done. Make sure to set your watch to the specific activity that you are undertaking to minimise error.
  3. Track your current average daily energy expenditure for the next 7 days. Just simply assess your daily values at the end of the week. Don’t forget to charge it whilst you’re sat at home so you don’t run out at work (because then your steps for the rest of the day clearly become null and void…)
  4. Assess your energy intake. Track your current average energy intake (My Fitness Pal is the easiest and most accessible option) for the next 7 days.
  5. Compare your recorded energy expenditure to your recorded energy intake – how do they compare?
  6. Set your target exercise energy expenditure based on all of these factors. For fat loss, you are aiming for a calorie deficit. For muscle gain, aim for a calorie surplus. So, in order to promote fat loss, you will need to increase your average daily energy expenditure from your current level. You can do this by increasing your target exercise energy expenditure, or by keeping the latter constant and increasing your physical activity throughout the day. It is your choice, but use the 7 day averages as a  baseline from which to progress.

For example, let’s say you have a goal of fat loss and you tracked the following values in your first week:

  • 340 kcal exercise energy expenditure
  • 1950 total daily energy expenditure
  • 2000 kcal daily energy intake

If you have hit a fat loss plateau, you may need to alter a) your expenditure or b) your intake, in order to promote a negative energy balance. Therefore, you may wish to add 100 kcal to your exercise energy expenditure i.e. equalling 440kcal, increasing your total daily energy expenditure to 2050kcal. Why 100kcal? I chose this number based on the fact that it would increase your exercise expenditure by approximately 30%, which is achievable with roughly 15-20 minutes additional cardio. You could choose a higher number should you wish, say increasing by 200kcal. There’s a balance between setting yourself a huge deficit to begin with which may bring faster results, but may also leave you with nowhere to progress in a few months when this expenditure has stopped promoting the changes that you wish.

The main point with setting your target energy expenditure is being consistent. Almost treat the expenditure as an arbitrary number, aiming to increase it from it’s current starting point if your goal is fat loss. And to increase your food intake accordingly, if your goal is muscle gain. Avoid trying to meticulously match your estimated intake and expenditure from your 7 days tracking. This can be highly misleading due to measurement error. So like I said, if your goal is fat loss, aim to increase your total daily energy expenditure, either through increasing your exercise energy expenditure (what you do in the gym / sports / runs etc.) or increasing your physical activity and NEAT levels (the rest of the day). Ultimately, the more active we are, the higher expenditure that we have, the more leeway we have in energy intake. And when you’re a monster around food like I am, what’s not to enjoy about that?

This is a method that I work with, with a lot of my clients. If you have any questions, just send me a message here and I’ll get back to you as quickly as possible. Enjoy the experimentation!



Chowdhury, E.A., Western, M.J., Nightingale, T.E., Peacock, O.J. and Thompson, D., 2017. Assessment of laboratory and daily energy expenditure estimates from consumer multi-sensor physical activity monitors. PloS one, 12(2), p.e0171720.


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