DON'T Come to the Gym to Burn Calories
A controversial opinion?
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Imagine this: The time is 6pm, and you’ve just walked into the gym after a long day at work. You hop onto the treadmill and walk on a steep incline for ten minutes. A good warm-up, you think to yourself, but also a nice way to sprinkle some light cardio into your routine. You glance down at the display to see that you’ve ‘only’ burned through 40 calories in that time. Excellent, you’ve now earned an extra half of a digestive biscuit with your cup of tea later. You feel slightly demoralised as you commence the rest of your gym routine, wondering how you’ll ever expend enough energy to lose the weight or look more lean than you currently do, without running a marathon.
If this sounds vaguely familiar - read on - this is NOT what gyms are designed for!
Fun fact:
Let’s re-visit that introductory piece again. Imagine slaving away on the treadmill, pretending that you’re enjoying yourself. The views probably aren’t great, and you would much rather be outside in the fresh air. Maybe it smells a bit musty and damp as the people on the machines next to you get a sweat on. You try to daydream the minutes away but you struggle to escape reality for longer than a few seconds. Well, sadly, this an an experience you share with 19th century prisoners in the UK.
This won’t surprise many of you, but treadmills, or more specifically, treadwheels, were actually used as a form of punishment in the 1800s. In fact, even though they could have been used to generate power to pump water, oftentimes, they simply served no other purpose than to keep the prisoners unhappy and punished.
I like to think that there’s a lesson here. The outdoors may be wet, miserable, dark, and/or cold at times, but human beings belong outdoors. A walk in nature is far more rewarding than on a treadmill. A run in nature gives much more beautiful views than a treadmill. Yes, you may need a warm shower afterwards if you go out in the rain, but you’ll need one regardless. Cycling, perhaps, could be more convenient indoors than outdoors, and there are obvious advantages to the rowing machines in the gym if you live far away from the water, or elliptical trainers if you have sore joints, but there is always a form of cardiorespiratory exercise that can be performed outside of the gym, for free. This leads onto my personal philosophy: The gym is a place to improve your strength and train your muscles first and foremost. Read on for some further reasoning…
A ‘NEAT’ Idea…
So, back to the title of this piece. The gym is NOT a place to visit with the goal of burning calories. For the average person, 30-minutes of exercise, whether that be treadmill jogging, cycling, weightlifting, circuit training, or swimming, is likely to ‘burn’ between 200 and 500 calories (kcal) at the very most. Whilst this may seem impressive, the upper end of 500kcal is the equivalent of 2 pints of lager, or 3 slices of toast. Simply put, that’s not a great deal.
The average male requires roughly 2500kcal per day, and the average female requires roughly 2000kcal per day. These guidelines are based on average energy expenditure each day, i.e. - how much energy is needed to fuel the average person for everything they do, every day. I’ve included a pie chart below, which outlines how we expend these calories each day - you may be surprised.
This chart highlights the first important fact regarding energy requirements: We burn the majority of these daily calories just simply by existing. Basal Metabolic Rate (BMR) refers to the energy required simply to perform life-sustaining actions, such as breathing, and moving blood around the body. It actually accounts for between 60-70% (that’s >1500kcal for the average man, and 1200kcal for the average woman) of all energy expended per day. The main driver behind BMR is lean mass , which is why men tend to expend more energy than women: More muscle = increased energy demand.
The next largest source of energy expenditure after BMR is called Non-Exercise Activity Thermogenesis, also known as NEAT. This refers to what many people may call physical activity, and may include but not be limited to: Fidgeting, taking the stairs, gardening, walking to work, cleaning the house, and playing with pets. Technically, NEAT refers to any energy expenditure that occurs outside of sleeping, eating, and structured exercise, such as gym workouts.
So, gym workouts must be the next biggest source of energy expenditure, right?! Sadly not. In fact, you burn more energy by eating and digesting your food than you do by taking part in structured exercise. This is known as the Thermic Effect of Feeding, or Food (TEF). This phenomenon also explains why, as exercise specialists, we are obsessed with protein. As a macronutrient, protein has a much higher TEF than carbohydrates and fats, meaning that it takes more energy to digest protein. Furthermore, adequate protein intake is a driving force behind muscle maintenance and development, which, as you now know, can lead to greater BMR, and further energy expenditure without you even having to exercise more.
So, how much of your total daily energy expenditure is your gym workout responsible for? Well, realistically, Exercise Activity Thermogenesis (EAT) probably accounts for 5-10%. A sad reality, but NOT a reason to stop going to the gym. As mentioned earlier, my personal philosophy is that the gym is a place to get stronger. Strength training improves and optimises the BMR portion of the chart, the largest piece, rather than the EAT portion, the smallest piece.
The ‘Afterburn’ Myth
Before I leave you, I can already hear cries of ‘what about high intensity training - I thought it burned more calories afterwards than during?’.
The logic behind this is that, under extremely high intensities, it takes the body longer to recover, and thus increases the energy requirement in the immediate post-exercise period. This has been called ‘Excess post-exercise oxygen consumption’, EPOC, ‘the afterburn effect’ and oxygen debt, amongst other names.
It does exist, but barely. One classic study1 demonstrated that it may be possible to expend up to 15% more energy after the workout than during. But remember, the stimulus must be high-intensity, not just a steady state, easy run. Simply put, if we take a 300kcal workout of sprint intervals, it may be possible to increase energy expenditure in the 12 hours afterward by an extra 45kcal (half a digestive biscuit, remember). I’ll let you decide whether it is worth it…
LaForgia J, Withers RT, Gore CJ. Effects of exercise intensity and duration on the excess post-exercise oxygen consumption. J Sports Sci. 2006 Dec;24(12):1247-64. doi: 10.1080/02640410600552064. PMID: 17101527.
Ben, this shouldn’t be controversial at all. It’s wonderful advice for anyone who has started or is maintaining a healthy exercise program. Thanks for this post