Forget about exercising to lose weight: you can't outrun a bad diet!

Forget about exercising to lose weight: you can't outrun a bad diet! 

A few days ago, an article showed up in my newsfood about a remarkable result of research done on the Hadza tribe in Tanzania, which still leads a traditional hunter-gatherer lifestyle. 
Despite walking an average of a multiple of ten thousands of steps every day, they barely need more calories than the average couch potato in a Western country. 
That same day I discussed with an old friend who had read the same news story. He told me how he had trained for a marathon in the past, but barely dropped any weight while doing so. Only when he spent a week on liquid foods at a spa, he succeeded in losing weight which he mostly thanks to the relaxed environment. Otherwise it was next to impossible. Apparently his body really clung to its precious body fat! 
 
But how was this possible? We didn't really know though we had our suspicions. I I could tell much about the same story. Yes, I'd drop weight pretty fast in the first few weeks of the cycling season or on a longer cycling holiday, but would get stuck at my regular (still too heavy) summer weight while I wasn't really inhaling tons of food. Except then for the Route des Cent Cols during which I could barely eat enough to stay fit and sleep well enough to climb all those mountains. 
 
Let's find out more about this particular research!
 
When Herman Pontzer set off for the rugged savannah of Tanzania to spend a summer with the local Hadza people, he thought he knew what he would find. As an evolutionary biologist, his aim was to measure how the Hadza’s hunter-gatherer lifestyle causes them to burn more energy. Because we all know the more exercise you do, the more calories you burn and the slimmer you become, right? Well no, not exactly.
Don’t expect any meaningful weight change in the long term from exercise alone.”
 
What Pontzer and his fellow researchers discovered flew in the face of received wisdom about how our metabolism works. Although the Hadza lead far more active lives than ours – routinely walking long distances, they undertake more physical activity daily than the typical American does in a week – their energy expenditure was no greater. They were burning the same number of calories as men and women from industrialised populations. Our bodies, concluded Pontzer, seem to maintain daily energy expenditure within a narrow window, no matter what lifestyle we lead. While obesity is largely caused by overconsumption, it appears there’s little we can do to change the calories we burn.
 
As Pontzer writes in his new book, Burn: The Misunderstood Science of Metabolism, “we have got the science of energy expenditure fundamentally wrong”.
 
A growing body of research supports this new understanding of metabolism. It has profound implications for how we tackle the obesity epidemic that has swept countries like the UK and US, but left the Hadza unscathed.
 
So why have we been barking up the wrong tree for so long?
The answer is that it’s hard to measure metabolism and, until recently, we lacked the scientific techniques to do so.
 
In the absence of good methods, people have been doing the best they can, which is making good guesses. The guesses have become the dogma. There’s this disconnect between the easy story and the more complex evolutionary story.
All the research we’ve done in the last 10 years, not just in Pontzer's ab but other people, too, points to diet as being the culprit here for obesity. It’s not sloth, it’s the food.
 
And when it comes to challenging the “easy story” the stakes could not be higher.
 
As Pontzer writes: Public health strategies stubbornly cling to the simplistic armchair engineer’s view of metabolism, hurting efforts to combat obesity, diabetes, heart disease, cancer and the other diseases that are most likely to kill us.
 
Those 10,000 daily steps you’ve been trying to achieve? A typical 70-kilogram adult burns about 250 calories while doing them, he explains. This is roughly equivalent to half a Big Mac. Climbing one flight of stairs burns about 3.5 calories – less energy than you’ll get from a single M&M.
 
It’s enough to send you back to the sofa, defeated. But it shouldn’t because exercise is vitally important for your health – it just won’t make you thin. “If you start a new exercise plan tomorrow and stick to it religiously, you will most probably weigh nearly the same in two years as you do right now,” he writes. “You should still do it! You’ll be happier, healthier and live longer. Just don’t expect any meaningful weight change in the long term from exercise alone.
 
So if squeezing in an extra trip to the gym each week won’t stop us piling on the pounds, what will?
The supervillain in Burn is the ultra-processed, highly flavoured foods in Western diets. While the Hadza have stuck to a plain diet of wholefoods, we have been seduced by an ever greater array of engineered delights. These won’t nourish us or fill us up, so we eat more of them.
 
What particularly is it about the food?
Is it sugar? No. Is it fats? No. It’s the fact we engineer our foods in labs and focus group test them to make sure you eat too much. That’s literally the point of these big industries: to make sure you buy as much as you can. That’s how they make money. Obesity has come up right alongside the availability and engineering of processed foods.”
 
Some of us eat more than others, of course, and some eat more ultra-processed food than others, for various reasons. Genes are part of the picture – though perhaps not in the way you’d expect.
 
You may think you have a fast or slow metabolism, but Pontzer suggests this perception usually translates as “I feel I can eat whatever I want and I never feel tempted or hungry outside of that”, or “I feel hungry all the time and if I don’t work really hard I will overeat”.
 
We know that is your brain’s management of your hunger and fullness and satiety, and we know people are wired differently and the genes that contribute to the variation in BMI [body mass index], they’re active in your brain, not in your fat or muscle cells. So it’s how you’re wired, it seems, that’s going to affect how fast you feel your metabolism is.
 
There are also external factors that influence how we eat. One is stress. It makes our brains take decisions about food that probably aren’t the healthiest. Comfort-eating and stress-eating are real. If COVID is having an effect on people’s waistlines, it’s as much about that [as anything].
 
Lowering the emotional and psychological stress in our lives – as well as physical stress caused by sleep deprivation – could help tackle overeating. Though Pontzer would be the first to acknowledge that in busy, modern lives revolving around working long hours in sedentary jobs, it’s easier said than done.
 
Obesity, then, stems from a complex interplay of biology and socio-economic factors. And once you’ve become overweight or obese, our highly evolved metabolisms make it incredibly difficult to shed the pounds gained.
 
Pontzer points to research such as the landmark study conducted during the 2010s on obese people who went to weight-loss bootcamps for the reality TV show The Biggest Loser. After 30 weeks of calorie reduction and exercise, the contestants had all lost weight, but tests showed that their metabolic rates had slowed down dramatically – they were in starvation mode, where cells burn energy more slowly as the body works to conserve calories. When researchers checked in with 14 of the contestants six years after the programme, their basic metabolic rates were still lower than expected and all but one had regained a considerable amount of weight.
 
It’s perverse – and depressing – but, writes Pontzer, “from an evolutionary perspective, it makes all the sense in the world”. It’s time, then, for a rethink of how our metabolic engines work.
 
But what do we do, meanwhile, to keep the weight off? 
 
Although he’s amused by the modern obsession with eating like our ancestors did, in the form of so-called Paleo diets, Pontzer says we can learn from the Hadza.
They stay thin because they eat a diet that doesn’t have these processed foods in it. I think 90 per cent of it is that simple.
 
We frequently complicate it with fad diets because we like to believe in the narratives around them. It’s appealing to think there might be a magic bullet. But there isn’t.
 
Every diet that works, works because it cuts calories. There are different ways to do that. There’s no magic. Every diet works if you stick to it.
 
The diet that works best for you depends on “your particular reward system and the variety of foods that satisfy you most on the fewest calories,” Pontzer writes. On a personal level, we can keep tempting treats out of reach. At a societal level, we will only tackle obesity by changing our food environment. Extra taxes on ultra-processed food might be one way. Making wholefoods cheaper and easier to come by, another.
 
How can the Hadza spend hundreds of calories a day on activity yet burn the same total number of calories a day as comparatively sedentary people in the U.S. and Europe? 
 
The number of calories you burn per day stays pretty consistent regardless of activity level; the average guy over age 50 burns about 2500 calories a day, depending primarily on body size, while the average woman will burn about 2000 calories a day. 
That’s your daily calorie budget. When you exercise more, your body simply lowers the number of calories it burns performing other functions, such as inflammation or hormone production. So the number of calories you burn per day — your metabolism — remains constant, whether you work out or not. 
 
The cost of activity is not really changing. Hadza  adults burn the same number of calories to walk a mile as Westerners do. It could be that people with high activity levels change their behaviour in subtle ways that save energy, like sitting rather than standing or sleeping more soundly. But our analysis of the METS data suggests that although these behavioural changes might contribute, they are not sufficient to account for the constancy seen in daily energy expenditure.
Another intriguing possibility is that the body makes room for the cost of additional activity by reducing the calories spent on the many unseen tasks that take up most of our daily energy budget: the housekeeping work that our cells and organs do to keep us alive.
 
Saving energy on these processes could make room in our daily energy budget, allowing us to spend more on physical activity without  increasing  total  calories  spent  per  day.  For  example,  exercise often reduces inflammatory activity that the immune system  mounts  as  well  as  levels  of  reproductive  hormones  such  as  estrogen. 
In lab animals, increased daily exercise has no effect on daily  energy  expenditure  but  instead  results  in  fewer  ovulatory  cycles and slower tissue repair. And extremes may lead some animals to eat their own nursing infants. Humans and other creatures  seem  to  have  several  evolved  strategies  for  keeping  daily  energy expenditure constrained. All of this evidence points toward obesity being a disease of gluttony rather than sloth. 
 
Extreme diets such as The Biggest Loser where people exercise a lot and eat very little can lower metabolism. If a diet can lower metabolism, why can’t we increase it?
 
From an evolutionary standpoint, it makes sense that we can turn our metabolism down, because that preserves our life in times of famine. But it makes no sense to turn your metabolism up, because once you do that, you need more food, and you increase your risk of starvation.
While it may seem that super athletes such as swimmer Michael Phelps turned up their metabolisms because they eat and burn tons of calories, that's not true. 
If you ramp up your training to an astronomical level, you can boost your energy burn for a bit, but even elite athletes such as Phelps settle back into the same range.

Conclusion

Physical activity remains vital – for regulating our metabolism, including our feelings of hunger and fullness, protecting us against every major disease, helping us live longer and maintaining weight loss. 
 
Just don't expect exercise is going to be the key to weight loss!
 
Read more at 'Excercise Paradox
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