If you spend a lot of a time in the same seat of a motor vehicle, you'll have formed a comfortable little relationship with its geography. As you settle in in the mornings, you'll notice how the fabric moves to accommodate the shape of your rear end, no matter how large, small, or deformed this may be.
You may also notice that the rear view mirror that you just changed at the end of the previous day's driving, now seems to be pointing too far downwards, so you might have to adjust it. Strange, you may remember having just adjusted it late yesterday after a day's driving, because it no longer seemed to be where you set it in the morning. What's going on?
The simple fact is that you've shrunk. That's right, even over the course of a day, the gaps between your backbone have been squeezed tighter by the force of gravity making your torso ever so much smaller. Not to worry, it's nothing that a good night's sleep can't fix, by helping stretch you out again. So the mirror will likely need adjusting again tomorrow morning.
If you've been driving the same vehicle for a long time, you might have noticed that these small changes have become much larger. The difference between where the mirror used to be and where it is now, could be much bigger even than the small changes that occur each day.
Could it be that your seat is getting lower? Of course that's always possible. But it's more likely that you're actually getting shorter over time. You might wonder though, could it really be by that much?
As someone who's always weighing and measuring people, I can assure you that it can. Two things I can usually guarantee in working in this area: 1. Men will always over-estimate their height, and 2. Women will always under-estimate their weight.
Let's look at height first: The significance of this was brought home to me recently when I was measuring a doctor in a group of doctors I was teaching (doctors are no different to the rest of us in this respect). I asked this guy before measuring him, how tall he though he was. He said 184cm. Now I'm not excessively dominant in the height department, but at 178cm, I could gauge the topography of this man's bald patch! Yet when I challenged him, he swore black and blue that he was definitely 184.
Why do we cling to such misconceptions? In the first place, men like to feel dominant, and height is one way of doing this. So even if you're not so vertically privileged, you like to give it all you've got. You probably haven't been measured since your youth, and that's the shortest you'd ever like to admit to. In truth, it's probably the tallest you've even been.
There are now two major studies carried out world-wide which have measured the height of a large group of people over 40-50 years. That way the change in height can be scientifically studied. In both of these pieces of research, men who lived to 80 years of age were shown to shrink by an average of 6cm. Women, on the other hand shrink an average of 10cm!
In men, the biggest drops in height have been amongst the tallest men. If you're a short-arse then, you can feel justified in the notion that if you live long enough, you may get to look those tall buggers that have always irritated you, squarely in the eye. The decrease in female height however is independent of their starting height.
Now I have a theory, which has yet to be disproven, that men are always teller than their mothers. (Think about it and if you can find an exception, I'll show you someone who has been starved, or ill most of his life). If this is the case, then jockeys will have very small mothers. And if jockey's mothers shrink by 10cm when they get older, there's not likely to be a lot of them!
The good news is that these are average decreases in height. The same studies have shown that people who are active most of their life, tend to shrink less than those who are inactive. This is another good reason to maintain an exercise or sport program throughout life. It helps your height, as well as your heart!
On the weight front: it's well known that women under-estimate their weight. When I weigh them, they typically express surprise and claim that my scales are wrong. But this is not the only way women fool themselves. It's well known for example, that the average woman under-estimates the amount of food she eats by around 30%; the average overweight woman by up to 80%. This is what I call the 'eye-mouth gap': the eye doesn't see (or want to see) what's going into the mouth. It might be expected then that women also tend to under-estimate their weight.
And while we're on self-deception, here are a couple of other little tricks we have to help avoid the truth. The first is what I call the 'exception rule'. This is the belief that people have that they don't normally eat too much, or too much of the wrong kind of food...except perhaps for that bit of extra cheese cake I had last night...or the big nosh-up the night before...or the party drinks the night before that...or...
For many people it's only an exception, like birthdays, public holidays, weekends and weekdays ending in a 'y' when they admit that they just might over-eat - a little!
Then there's the 'foot-brain' gap, which is the movement version of the 'eye-mouth gap'. This says that the brain never really knows how many steps the feet have done during the day. Overweight men, in particular tend to over-estimate how active they are by 30-40%. And they wonder why they're overweight!
This one makes sense though: If you're very overweight, moving can be painful. So walking a kilometer can feel like walking 10 kilometers. Hence, at the end of the day, it always seems like you've done more than you really have.
Taken all together, these little self deception tricks explain a lot about what is going on in the real world, in contrast to what's going on in our brains. It also explains why you think your truck/car seat might need replacing, and why you're steadily losing height while gaining width as you get older. Just remember this the next time you adjust your rear-vision mirror. And remember, the scales might not lie, but we do!
Dr Garry Egger MPH PhD
Professor of Lifestyle Medicine at Southern Cross University and an Advisor to the World Health Organisation and Governments in lifestyle and chronic disease.
You may also notice that the rear view mirror that you just changed at the end of the previous day's driving, now seems to be pointing too far downwards, so you might have to adjust it. Strange, you may remember having just adjusted it late yesterday after a day's driving, because it no longer seemed to be where you set it in the morning. What's going on?
The simple fact is that you've shrunk. That's right, even over the course of a day, the gaps between your backbone have been squeezed tighter by the force of gravity making your torso ever so much smaller. Not to worry, it's nothing that a good night's sleep can't fix, by helping stretch you out again. So the mirror will likely need adjusting again tomorrow morning.
If you've been driving the same vehicle for a long time, you might have noticed that these small changes have become much larger. The difference between where the mirror used to be and where it is now, could be much bigger even than the small changes that occur each day.
Could it be that your seat is getting lower? Of course that's always possible. But it's more likely that you're actually getting shorter over time. You might wonder though, could it really be by that much?
As someone who's always weighing and measuring people, I can assure you that it can. Two things I can usually guarantee in working in this area: 1. Men will always over-estimate their height, and 2. Women will always under-estimate their weight.
Let's look at height first: The significance of this was brought home to me recently when I was measuring a doctor in a group of doctors I was teaching (doctors are no different to the rest of us in this respect). I asked this guy before measuring him, how tall he though he was. He said 184cm. Now I'm not excessively dominant in the height department, but at 178cm, I could gauge the topography of this man's bald patch! Yet when I challenged him, he swore black and blue that he was definitely 184.
Why do we cling to such misconceptions? In the first place, men like to feel dominant, and height is one way of doing this. So even if you're not so vertically privileged, you like to give it all you've got. You probably haven't been measured since your youth, and that's the shortest you'd ever like to admit to. In truth, it's probably the tallest you've even been.
There are now two major studies carried out world-wide which have measured the height of a large group of people over 40-50 years. That way the change in height can be scientifically studied. In both of these pieces of research, men who lived to 80 years of age were shown to shrink by an average of 6cm. Women, on the other hand shrink an average of 10cm!
In men, the biggest drops in height have been amongst the tallest men. If you're a short-arse then, you can feel justified in the notion that if you live long enough, you may get to look those tall buggers that have always irritated you, squarely in the eye. The decrease in female height however is independent of their starting height.
Now I have a theory, which has yet to be disproven, that men are always teller than their mothers. (Think about it and if you can find an exception, I'll show you someone who has been starved, or ill most of his life). If this is the case, then jockeys will have very small mothers. And if jockey's mothers shrink by 10cm when they get older, there's not likely to be a lot of them!
The good news is that these are average decreases in height. The same studies have shown that people who are active most of their life, tend to shrink less than those who are inactive. This is another good reason to maintain an exercise or sport program throughout life. It helps your height, as well as your heart!
On the weight front: it's well known that women under-estimate their weight. When I weigh them, they typically express surprise and claim that my scales are wrong. But this is not the only way women fool themselves. It's well known for example, that the average woman under-estimates the amount of food she eats by around 30%; the average overweight woman by up to 80%. This is what I call the 'eye-mouth gap': the eye doesn't see (or want to see) what's going into the mouth. It might be expected then that women also tend to under-estimate their weight.
And while we're on self-deception, here are a couple of other little tricks we have to help avoid the truth. The first is what I call the 'exception rule'. This is the belief that people have that they don't normally eat too much, or too much of the wrong kind of food...except perhaps for that bit of extra cheese cake I had last night...or the big nosh-up the night before...or the party drinks the night before that...or...
For many people it's only an exception, like birthdays, public holidays, weekends and weekdays ending in a 'y' when they admit that they just might over-eat - a little!
Then there's the 'foot-brain' gap, which is the movement version of the 'eye-mouth gap'. This says that the brain never really knows how many steps the feet have done during the day. Overweight men, in particular tend to over-estimate how active they are by 30-40%. And they wonder why they're overweight!
This one makes sense though: If you're very overweight, moving can be painful. So walking a kilometer can feel like walking 10 kilometers. Hence, at the end of the day, it always seems like you've done more than you really have.
Taken all together, these little self deception tricks explain a lot about what is going on in the real world, in contrast to what's going on in our brains. It also explains why you think your truck/car seat might need replacing, and why you're steadily losing height while gaining width as you get older. Just remember this the next time you adjust your rear-vision mirror. And remember, the scales might not lie, but we do!
Dr Garry Egger MPH PhD
Professor of Lifestyle Medicine at Southern Cross University and an Advisor to the World Health Organisation and Governments in lifestyle and chronic disease.
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