Exercise won’t trim your waistline but it will keep your brain in shape
LET me be honest here, I’m not a big fan of exercise. I make myself do daily press-ups and squats, and though I enjoy brisk walks, I never, ever enjoy running.
The main reason I keep at it is because of overwhelming evidence of the multiple benefits that exercise brings. In fact, the latest research suggests it may be even more beneficial for preserving a sharp memory than had been suspected.
But for those who spend lots of time running on treadmills or pedalling away at their exercise bike in the hope of burning off lots of calories, there comes bad news.
Because a new study shows that exercise is even less effective at helping people lose weight than we previously believed to be true.
We have known for some time that exercise alone is not a great way to lose weight. That is mainly because people overestimate how many calories they burn when they are exercising (by as much as three or four-fold, according to at least one study).
And they underestimate how many calories there are in the snack which they reward themselves with after they have been for a run.
In fact, the calories burned by exercise are surprisingly modest.
A few years ago, I had my calorie burn accurately measured while running a mile. This was done using a mask attached to a device that measured how much oxygen I was consuming, and how much carbon dioxide I was breathing out.
The test showed that I burn around 120 calories a mile when running, and about 60 calories a mile when walking.
WhIch means that if I ate a muffin (roughly 400 calories) then to burn those calories, I would have to run just over three miles or walk six miles, which would take around two hours. But it turns out that those calorie-burning figures are hopelessly optimistic.
The findings of the new study show that, over time, your body compensates for the extra calories you’ve burnt through exercise, by slowing your metabolism down.
Yes, down, not speeding it up.
This is exactly the opposite to what we had been led to believe.
The assumption has always been that if you exercise more, your metabolism speeds up. While this seems to be true in the short term, it isn’t in the long term. The new study, from the University of
Roehampton, looked at data that had been collected by the International Atomic Energy Agency. Scientists there had carefully tracked the amount of calories that more than 1,750 volunteers burned while going about their normal lives. What the Roehampton team found was that although people use up more calories when they are exercising, their bodies simply compensate by burning fewer calories than normal when doing things such as sleeping.
It turned out that the calories used to keep their bodies ticking over (known as basal energy expenditure) fell by 28 per cent during periods when they were doing regular exercise.
Which, in turn, means the overall impact on our waistlines of doing exercise is less than we might have expected.
There was particularly bad news for people who were hoping to use exercise to slim down, because the effect is even greater in people who are overweight or obese.
ThIS latest study found that if you have a higher BMI (body mass index), then only half the calories you burn while doing exercise translate into real calorie loss at the end of the day. In other words, if you are overweight, then far from burning 120 calories every time you run a mile, once you include the impact that running has on reducing your metabolic rate, you only really burn through 60 calories. Depressing, yes, but this is no excuse to hang up your running shoes. There is plenty of research showing that keeping active will add healthy years to your life, reduce your risk of developing a range of chronic diseases, help you sleep better, improve your mood and even perk up your sex life. Being active is also good for your brain. A recent study by scientists from the National Institute on Aging, published in the journal NeuroImage, showed that regular exercise leads to the creation of new brain cells, particularly in the area of the brain associated with memory, which hopefully means you are less likely to develop Alzheimer’s disease and other forms of dementia. So do keep exercising, but don’t expect that alone to make much difference when you stand on the scales.