Postdate: 08 October 2018
Exercise requires energy and therefore burns calories – that’s a given. So how come it makes so little difference to our weight? You can find out the answer in this blog by cardiologist and Tsuru expert Dr. Ruud van Langeveld.
Physical activity burns more calories. Sounds good, you might think. But there are some evidence-based reasons why moving more might not really help you lose weight.
Reason 1: you overestimate the benefit of physical activity.
First and foremost, the number of calories you burn through exercise is not all that spectacular. To demonstrate this, Canadian scientists got a bunch of volunteers to each run off 200 kilocalories on a treadmill. But the general belief among the volunteers was that they had actually burned 800 kilocalories – in other words, four times as much as they really had.
Therefore, you might think you’re exercising away an entire meal, when in fact it’s only a small snack. The motion factor of somebody who spends the whole day in front of their computer and then does no more than flick between TV channels once they’re home is about 1.3. If they were to instead add some physical activity into their day and start really pushing themselves in the gym, this would rise to 1.7.
Based on a basal metabolic rate of 1,500 kcals, the difference is ‘only’ 500 kcals. So while you may have been working hard and sweating it out, and your muscles may clearly be in need of a rest, when all is said and done you’ll have burned less than you would expect.
Reason 2: your body automatically tends to compensate.
Another reason is that your body automatically tends to replenish lost energy. In the example above of burning an extra 500 kcals through physical activity, this difference would be wiped out because your body would simply make savings somewhere else. Evidence suggests that this is achieved by eating more, and that the process largely takes place without you even noticing. For example, you might get hungry after exercising, or you might feel lazy and do nothing for the rest of the day. This research has proven that this can be the case.
The idea that you burned off a whole meal yesterday evening, and so it should be possible to enjoy something extra today, cancels out any weight loss.
“Exercising? You see, it makes no sense at all!”
Of course, that’s over-simplifying matters. Even if you’re not exercising simply to lose weight, moving more is certainly a good idea for other reasons. Physical activity and exercise boost your health and reduce the risk of heart disease and other chronic conditions. What’s been scientifically proven (though somewhat exaggerated) is that it’s better to be a little bigger but still healthy by being active than it is to be sedentary, unhealthy and slimmer.
The most important lesson from all this? Don’t get your hopes up too much. Don’t think that exercise makes you immune to weight gain; recognise that the number of calories you consume should still be modest. And if you do want to kick those kilos into touch, it’s far better to cut down on sugary drinks and snacks.