Understanding energy balance:
For the purpose of this blog, I’d like to further your understanding of just exactly what non exercise activity thermo-genesis (NEAT) is, how it can relate to your lifestyle and specifically whether you need to be mindful of its inclusion in your lifestyle. I’d like to begin by highlighting just what NEAT actually is; and clarify that it is unplanned, unstructured increases in activity levels. This can be things such as taking the stairs, parking an extra few meters from your destination, mopping your floors and anything else which is not deemed to be exercise by definition. This sort of activity is extremely important in our day to day lives as we are currently faced with rising rates in obesity and obesity related health conditions. Our lack of activity is unfortunately exacerbated through increased leisure time and more sedentary work environments (Peterman, Kram & Byrnes, 2012). Something to also consider is that even though you may be meeting the American College of Sports Medicine (ACSM) guidelines for physical activity (within the gym), you may spend the rest of your day relatively inactive which still poses increased risk factors for cardiovascular and metabolic health issues which is a scary thought (Peterman, Kram & Byrnes, 2012). What I’d like to do though, is put your mind at ease and ensure you know just how much you need to be doing per day to keep your body as healthy and happy as possible.
How does your body expend energy?
To understand the affects that our movements and our day to day life have on our body, we need to quantify how we in fact burn energy in the first place. Firstly, we have what is known as our basal metabolic rate (BMR) which accounts for all of the energy which we burn at rest, such as sleeping. This output equates for roughly 60% of our total daily expenditure and has multiple factors which contribute to this output such as age, sex, muscle mass, sleep quality and overall health. Secondly, and at no surprise, we can burn up to 25% of our daily energy through physical activity. This output is again affected by age, sex, muscle mass, duration of activity and training intensity. Thirdly we have our non-exercise activity which is roughly 7% and affected simply by how much we move our bodies during the day. Lastly, digestion can equate to 8% of our daily output (Brychta, Wohlers, Moon & Chen, 2010). Generally speaking, these values remain relatively constant for everybody however it is the total amount that is expended which will be different from person to person.
How many calories do we burn?
As I have just mentioned, everybody is going to burn a slightly different amount of calories throughout their day and as a general rule, this amount decreases with age. To give you an example, Elia, Ritz and Stubbs (2000) stated that as we age, there is a decrease in men of 0.69 megajoules (MJ) per day per decade, which is approximately 165 calories a day less than the decade before. This number in women is 0.43 MJ or 102 calories. These numbers are based on a total daily energy expenditure which takes into account the 4 above mentioned variables of energy output. Something to consider is that a positive energy intake of between 100 and 125 calories per day, can lead to a weight gain of between 2kg and 6kg a year, which can quickly add up to a large amount in a few decades (Brychta, Wohlers, Moon & Chen, 2010). Something to consider however is the positive relationship between muscle mass and caloric expenditure. Yagi et al. (2014) were able to equate a relationship of R = -0.57 between overall muscle mass, and visceral fat adiposity with this inverse relationship sitting at R = -0.62 when specifically looking at lower limb mass. To give you a more practical example however, for every 1kg of muscle mass added to your body, you can expect to burn roughly 20 calories per day more than without that tissue. Whilst it doesn’t sound like a lot initially, it has the potential to add up in your favour over time, as you strength train with the intention of gaining muscle mass.
Just how much can we burn by increasing our output?
One of the best studies I have come across to answer this question was published by Peterman, Kram and Byrnes (2012) who investigated the energy output calculated through passive cycling. Yes, you read that correctly, they investigated what we can increase our output to by simply having a bike move our legs for us. 11 participants were given a few different protocols in which the increase from BMR in energy expenditure was measured. The protocols were either single leg or double leg at a cadence of either 60 RPM or 90 RPM. These measures were also put against an active unloaded protocol at the same cadence. Results were as follows:
Table 1. Energy Expenditure in active and passive cycling conditions as compared to resting energy rate. Adapted from Peterman, Kram & Brynes, (2012).
Energy Expenditure (calories / min)
Pre Treatment 1.28 ± 0.23
60 RPM
Passive 1 leg Passive 2 leg Active no load
1.49 ± 0.28 1.78 ± 0.35 2.06 ± 0.43
90 RPM
Passive 1 leg Passive 2 leg Active no load
1.85 ± 0.25 2.51 ± 0.58 3.28 ± 0.50
Whilst the above mentioned study takes into account the benefit simply moving our bodies can have, we also need to look at specific conditions such as energy expenditure within the gym. Myers et al. (2019) reported caloric expenditure of between 400 and 500 calories per 45 minute aerobic gym session within a population of 24 overweight women. This intervention was able to show a reduction in the participants BMI with significant decreases in fat free mass. A resistance training specific intervention also showed an increase in metabolic activity post exercise which was able to last for up to 90 minutes post session cessation. This intervention was conducted by Benton & Swan (2009) who used an 8 exercise, 3 set protocol of 8 to 12 repetitions a set and found that Vo2 was elevated from 2.9ml/kg to 4.4ml/kg at the 0 to 4 minute mark, and remained elevated to 3.3ml/kg for up to 90 minutes after exercise. Their protocol only lasted 21 minutes and was able to burn on average 131 calories in that time. This equates to almost 400 calories in an hour resistance training workout with the added benefit of burning a greater amount of calories at rest post exercise.
Practical applications:
To implement this data correctly, you first need to understand where you are within your training goals and current lifestyle. If you are an active person to begin with, you probably need not worry about implementing a “steps per day” goal or trying to increase your output too heavily, as it is probably already quite high. You might in fact be trying to build muscle tissue and are struggling to do so, in this case I think you need to address your caloric intake and ensure you are eating enough. On the other end of the spectrum, if you are very sedentary and are not hitting the gym very hard, you probably need to move more in any way you can to ensure you are reducing your risk of health problems. If you are somewhere in between, I still suggest you tread carefully when it comes to just moving for the sake of it. Yes it is a good idea, but if you are trying to build muscle, then that needs to be your priority. If you are trying to increase your cardiovascular fitness, you may also be already doing enough. I suggest over all, that you write down your goals, calculate your energy output using a heart rate device, calculate your energy intake using an app on your phone and then go from there. Doing 10,000 steps a day for the sake of it could be what you need, or the opposite of what you need. Understand your “why” first and then go from there.
References:
Benton, M. J., & Swan, P. D. (2009). Influence of resistance exercise volume on recovery energy expenditure in women. Eurpoean Journal of Sports Science, 9(4), 213-218.
Brychta, R., Wohlers, E., Moon, J., & Chen, K. Energy
expenditure: measurement of human metabolism.
IEEE Engineering in Medicine and Biology Magazine, 29(1), 42-47.
Elia, M., Ritz, P., & Stubbs, R.J. (2000). Total energy expenditure in the
elderly. European Journal of Clinical
Nutrition, 54(3), s92-s103.
Myers, A., Dalton, M., Gibbons, C., Finlayson, G., & Blunden, J. (2019).
Structured, aerobic exercise reduces fat mass and is particularly compensated
through energy intake but not energy expenditure in women. Physiology and Behaviour, 199, 56-65.
Peterman, J.E., Kram, R., & Byrnes, W.C. (2012). Factors affecting the
increased energy expenditure during passive cycling. European Journal of Applied Physiology, 112(9), 3341-3348.
Yagi, S., Kadota, M., Aihara, K., Nishikawa, K., Hara, T., Ise, T., Ueda, Y.,
Iwase, T., Akaike, M., Shimabukuro, M., Katoh, S., & Sata, M. (2014).
Association of lower limb muscle mass and energy expenditure with visceral fat
mass in healthy men. Diabetology and
Metabolic Syndrome, 6(1), 27-32