Colette Sheridan: Why having your cake and eating it never works in diet stakes

Exercise doesn’t help us lose weight - according to a new book - writes Colette Sheridan
Colette Sheridan: Why having your cake and eating it never works in diet stakes

HEALTH KICK: But if you’re walking in a bid to lose weight, your body’s metabolism may have the last word, warns Colette Sheridan

I’VE been feeling a little smug lately, as I diligently go for a brisk 45-minute walk in a public park every day, even when it’s raining.

Granted, on the wet days, I’m like a bitch, cursing the weather and wishing I was at home with my feet up, guzzling something calorific.

But it’s because of calorific food that I’m obliged to exercise. Or so I thought.

Like a lot of people, Covid-19 has resulted in me gaining weight. All that is needed is a little bit of punishment. And really, on a good dry day when the sun peaks out, marching around the park listening to the radio through my ear phones is not such a sacrifice.

But now, it seems, I’ve been wasting my time.

Believing in the ‘no pain, no gain’ mantra, our thinking is hard-wired to reckoning that unless we suffer physically, by exerting ourselves, we have no hope of losing weight. ‘Gain’, in this context, is walking or running our way to thinness.

However, a book out this week, entitled Burn: The Misunderstood Science Of Metabolism by Professor Herman Pontzer, says that exercise doesn’t help us lose weight because we burn the same amount of calories each day, regardless of how we live, be it in a sedentary way or a physically active existence.

Herman Pontzer, professor of evolutionary anthropology at Duke University, North Carolina, has done studies with hunter-gatherer tribes and reveals how exercise doesn’t increase our metabolism.

Instead, we burn calories within a very narrow range, no matter how high or low our level of activity.

This was a intelligent evolutionary strategy to survive in times of famine. But now, it seems to lead us to obesity.

As Professor Pontzer argues, most of us can’t exercise our way to becoming slim. He has spent a lot of time with the Hadza, a hunter-gatherer people in northern Tanzania. The Hadza move about five hours a day, walking more than eight miles, getting more physical activity than the rest of us get in a week. Yet, relative to body weight, their energy expenditure is almost on a par with ours.

That seems all wrong. Surely, exercise burns off calories and fat?

Professor Pontzer’s starting point was to compare how the historical shift to a more sedentary lifestyle has changed the amount of calories we burn. Speaking on BBC Radio 4, he said that the big surprise is that it hasn’t.

“What we’ve learnt is that we burn the same number of calories every day, regardless of lifestyle,” he said. 

“Our lifestyle determines how we burn them.”

According to the scientist, people who are more active do burn more calories through exercise, but they spend less energy on other things such as immune functioning. So it balances out.

To lose weight, we should focus on diet. If we gain weight, it’s because we’re consuming more calories than we burn off.

That everyone burns the same number of calories, regardless of our activity levels seems unfair. How about exercise fiends, working up a sweat? I haven’t got to that stage yet.

However, I’m proof that exercise doesn’t necessarily lead to weight loss. I’m on a plateau — maintaining the same weight, regardless of walking.

But I thought it would be only a matter of time before my efforts would be rewarded. In truth, I’ve been trying to have my cake and eat it. Literally. Coffee cake, to be precise, and other nice food, thinking that walking swiftly would do the trick.

But that was never going to work. I kind of know I’ve been fooling myself.

Professor Pontzer puts diet under the spotlight when it comes to losing weight. He also says that if there’s one kind of food “that gets you into trouble, it’s these ultra-processed foods”.

The reason they’re so dangerous is “that they give us mixtures of sweet and savoury that taste so good, but our brain does a bad job of regulating how much energy you take in because these are flavours and combinations that our Palaeolithic brains aren’t evolved to handle.”

So, should we put our feet up and graze on plant food? No, actually, We need to exercise to keep our body systems and signals functioning optimally, even if it won’t slim us down.

The Hadza, who are by our standards over-active, remain remarkably healthy into old age. 

So maybe we can walk or jog our way to longevity — but not slimness, unfortunately.

Yet, if you take a programme like Operation Transformation, which combines diet with vigorous (by my standards) exercise, moving a lot seems to help knock inches off the waists of the participants. I suppose it’s more a way of toning up.

Professor Pontzer says we are designed to run. Just don’t expect to get slim as a result.


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