When it comes to calories, sometimes the numbers simply don’t add up. Check the tally on your smartwatch or Peloton, keep track for a few months, and then check the bathroom scale. No matter how many calories you’ve torched, the resulting weight loss will be less than you hoped.
That’s the riddle at the heart of a recent review published by Lewis Halsey, who heads the University of Roehampton’s Behaviour and Energetics Lab, in the journal Physiological and Biochemical Zoology. It’s clear from the review’s title, “The Mystery of Energy Compensation,” that final answers aren’t yet forthcoming – but as Halsey explains, a flurry of studies using new techniques to measure calorie burn are overturning some long-cherished tenets of conventional wisdom about the effects of exercise.
The key technology in the debate is “doubly-labelled water,” which is water that contains rare – and easy trackable – isotopes of both hydrogen and oxygen. In the 1950s, a researcher named Nathan Lifson figured out how to accurately measure the total daily calorie burn of mice by having them drink some of this special water and then collecting urine over subsequent days to see how long it took to metabolize. The problem: it would have cost more than $300,000 to run the same experiment on a human.
It’s only in the past few decades that the cost has dropped enough for scientists to use the technique widely, with a current price of about $750 per person. The results have been unexpected, most notably when a team led Herman Pontzer of Hunter College in New York (he’s now at Duke University) tried it with the Hadza, a group of hunter-gatherers who still live a traditional lifestyle in northern Tanzania.
Hunting with bow-and-arrow and foraging with digging sticks, the typical Hadza adult gets more exercise in a day than the average couch-bound Canadian gets in a week. But as Pontzer recounts in Burn, an entertaining book about the new science of metabolism that he published earlier this year, the results defied his and everyone else’s expectations. Once you take into account factors such as age and body size, Hadza adults burn pretty much exactly the same number of calories each day as Canadians – and as everyone else from populations around the world tested with doubly-labelled water.
We know, from the fundamental laws of thermodynamics, that physical activity must burn calories. So the fact that high levels of physical activity don’t lead to greater overall calorie burn means that we must have other ways of saving calories: the “energy compensation” of Halsey’s title.
The first question is how we do it. One theory is that we fidget and move around less after exercise. Another is that we spend less energy on under-the-hood bodily functions like immune response and tissue repair. A third is that our cells become more efficient at converting food into usable energy, squeezing more power out of each calorie we eat. At this point, Halsey says, there’s simply not enough evidence to choose between them.
The second question is what it means for our ongoing societal struggle to lose weight. Another double-labelled water study, published in July, suggests that energy compensation kicks into high gear when you’re losing weight, but is less of a factor when your weight is stable or increasing. That’s consistent with the widespread view that exercise is more useful for preventing weight gain than promoting weight loss.
Even when energy compensation is working against you, it doesn’t erase all your efforts. In one study that’s often cited as evidence of the effect, people training for a half-marathon didn’t burn as many calories as their training predicted – but they still burned about 30 per cent more calories than before they started training, which may be enough to move the needle of the scale.
The broader message, though, is that good health isn’t just about hitting a certain weight. In Burn, Pontzer suggests that some of the health benefits of exercise may be a direct result of energy compensation. If your body foils your weight-loss goals by ramping down immune function, that might reduce chronic low-grade inflammation in response to things like food and allergens, while preserving the ability to respond to real threats. The same is true of the body’s stress response.
Halsey, too, remains convinced that physical activity is crucial to health, and even plays a role in weight loss – but not in the simple way the numbers suggest.
“We need to get over the idea that if we start doing, for example, 300 calories of exercise per day, then we have burned that many more calories per day,” he says. “That appears not to be the case, in the long run.”
Alex Hutchinson is the author of Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance. Follow him on Twitter @sweatscience.
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Nova Scotia reports 23 new COVID-19 cases, 26 recoveries – Vancouver Is Awesome
HALIFAX — Nova Scotia is reporting 23 new cases of COVID-19.
Thirteen cases have been identified in the central zone, which includes Halifax, six cases are in the western zone, three cases have been found in the northern zone and one case is in the eastern zone.
Authorities say 26 recoveries have also been reported.
The province now has 160 active infections with 15 people in hospital, four of whom are in intensive care.
Officials also reported that two schools received COVID-19 exposure notices Thursday, both of them in the Amherst area.
And officials continue to monitor an outbreak of the disease in a non-COVID unit at Valley Regional Hospital in Kentville where five cases of COVID-19 have been identified.
This report by The Canadian Press was first published Oct. 22, 2021.
This story was produced with the financial assistance of the Facebook and Canadian Press News Fellowship.
The Canadian Press
Note to readers: This is a corrected story. A previous version based on an erroneous Health Department news release said there were 11 people in hospital.
Get COVID-19 and flu shot at the same time – Windsor Star
You can get a COVID-19 vaccination and annual flu shot at the same time, Windsor Essex County Health Unit director of health protection Kristy McBeth said Thursday.
The National Advisory Committee on Immunization, which makes recommendations on the use of vaccines in Canada, recommended recently that the COVID-19 vaccine can be administered at the same time or any time before or after other vaccines, including the flu shot.
Previously, the committee had recommended that COVID-19 vaccines be administered at least 28 days before or 14 days after other shots as a precautionary measure.
After reviewing the evolving evidence on COVID-19 vaccines and considering the extensive data on administering other routine vaccines at the same time or within days of each other, the committee has determined that the earlier, precautionary approach is no longer necessary.
The new recommendation is expected to help the rollout of the flu shot this fall as well as make it easier for people to get other vaccines they may have missed during the pandemic.
The flu shot is free in Ontario and available at doctors’ offices and pharmacies. Hospitals, long-term care homes, doctors’ offices, walk-in clinics and pharmacies here have already received their supplies.
People over age 65 and those at risk of complications from flu have been given priority and are receiving the vaccine now. The shot will be available to the general public in November.
The health unit will begin promoting the shot more widely next month.
“We will be doing some extra promotion, urging people to get it,” McBeth told the health unit’s board of directors.
Between 150,000 and 200,000 doses are expected to be administered here this season, up from 97,000 last year.
Ontario has ordered 7.6 million doses this year, 1.4 million more than last year, Health Minister Christine Elliott said Tuesday.
There were few cases of flu last season because many people worked from home, their children learned remotely and the economy and society were locked down.
But more cases are expected this season because many people have returned to offices, schools have reopened and many restrictions have been lifted, allowing people to be out in the community more and to socialize and travel.
People are being urged to get the flu shot to avoid overwhelming hospitals that are still caring for COVID-19 patients.
Canada scraps COVID-19 travel advisory; Ontario to end mask, vaccine rules by March
Canada has scrapped an official advisory urging its citizens to shun non-essential foreign travel, given its successful campaign to inoculate people against COVID-19, the country’s top medical officer said on Friday.
Hours later, Canada’s most populous province, Ontario, issued a timeline to lift all remaining COVID-19 restrictions, with the aim of removing all proof of vaccination and mask requirements by March 2022.
Canada’s travel warning was issued in March 2020, when the COVID-19 pandemic erupted.
Ottawa removed the advice to avoid unnecessary travel late on Thursday, however it is still telling people to avoid cruise ship travel outside of the country.
“The beginnings of the transition away from the more blanket approach really recognizes vaccines are very effective at preventing severe outcome,” Chief Medical Officer Theresa Tam told a briefing.
According to official data, just under 82% of eligible Canadians had been fully vaccinated against COVID-19 by Oct 8.
Tam said the latest surveillance data showed “a continued decline in disease activity nationally and in most jurisdictions.”
“Now is not the time to just freely go wherever,” she added, citing high cases of coronavirus in some nations.
Ontario laid out a six-month timeline to lift all COVID-19 restrictions, starting with removing capacity limits in the “vast majority” of public venues on Oct. 25, and culminating in an end to all mask and proof of vaccination requirements by March.
The timeline will be dependent on “the absence of concerning (pandemic) trends,” it said in a statement.
“This plan is built for the long term,” Premier Doug Ford said. “It will guide us safely through the winter and out of this pandemic, while avoiding lockdowns and ensuring we don’t lose the hard-fought gains we have made.”
Ontario spent much of the past 18 months in some form of lockdown due to high infection rates and hospital bed occupancy of COVID-19 patients.
(Reporting by David Ljunggren in Ottawa and Moira Warburton in Vancouver; Editing by Paul Simao and Bill Berkrot)
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