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Exercise & Our Metabolism

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Today we will be looking at two different articles that were in the New York Times each looking at Metabolism and Weight Loss. Each article was looking at different groups of people and looked at metabolism and weight loss from different angles. Whilst neither necessarily contradict one another rather they confirmed that metabolism is complex and there are multiple angles you need to consider as you fuel your body for training, life or weight loss.



Gina Kollata , reviewed a new paper that was published in Science that upends thinking about how metabolism really works. here are some of the highlights from this article.


Everyone knows conventional wisdom about metabolism: People put pounds on year after year from their 20s onward because their metabolisms slow down, especially around middle age.

Women have slower metabolisms than men. That’s why they have a harder time controlling their weight. Menopause only makes things worse, slowing women’s metabolisms even more.

All wrong! Using data from nearly 6,500 people, ranging in age from 8 days to 95 years, researchers discovered that there are four distinct periods of life, as far as metabolism goes.

They also found that there are no real differences between the metabolic rates of men and women after controlling for other factors.Up until this study, the assumption was energy expenditure was constant per pound but it seems it’s based on age .


Metabolic research is expensive, and so most published studies have had very few participants. But the new study’s principal investigator, Herman Pontzer, at Duke University, said that the project’s participating researchers agreed to share their data.

There are more than 80 co-authors on the study. By combining efforts from a half dozen labs collected over 40 years, they had sufficient information to ask general questions about changes in metabolism over a lifetime.


All of the research centers involved in the project were studying metabolic rates with a method considered the gold standard — doubly labeled water. It involves measuring calories burned by tracking the amount of carbon dioxide a person exhales during daily activities.The investigators also had participants’ heights and weights and percent body fat, which allowed them to look at fundamental metabolic rates. A smaller person will burn fewer calories than a bigger person, of course, but correcting for size and percent fat, the group asked: Were their metabolisms different?


“It was really clear that we didn’t have a good handle on how body size affects metabolism or how aging affects metabolism,” Dr. Pontzer said. “These are basic fundamental things you’d think would have been answered 100 years ago.”

Central to their findings was that metabolism differs for all people across four distinct stages of life. There’s infancy, up until age 1, when calorie burning is at its peak, accelerating until it is 50 percent above the adult rate.Then, from age 1 to about age 20, metabolism gradually slows by about 3 percent a year. From age 20 to 60, it holds steady. And, after age 60, it declines by about 0.7 percent a year. Once the researchers controlled for body size and the amount of muscle people have, they also found no differences between men and women. As might be expected, while the metabolic rate patterns hold for the population, individuals vary. Some have metabolic rates 25 percent below the average for their age and others have rates 25 percent higher than expected. But these outliers do not change the general pattern, reflected in graphs showing trajectory of metabolic rates over the years.



One of the findings that most surprised Dr. Pontzer was the metabolism of infants. He expected, for example, that a newborn infant would have a sky-high metabolic rate. After all, a general rule in biology is that smaller animals burn calories faster than larger ones.Instead, Dr. Pontzer said, for the first month of life, babies have the same metabolic rate as their mothers. But shortly after a baby is born, he said, “something kicks in and the metabolic rate takes off.”


The group also expected the metabolism of adults to start slowing when they were in their 40s or, for women, with the onset of menopause.


But, Dr. Pontzer said, “we just didn’t see that.”

The metabolic slowing that starts around age 60 results in a 20 percent decline in the metabolic rate by age 95. Dr. Klein said that although people gain on average more than a pound and a half a year during adulthood, they can no longer attribute it to slowing metabolisms.


Energy requirements of the heart, liver, kidney and brain account for 65 percent of the resting metabolic rate although they constitute only 5 percent of body weight, Dr. Klein said.

It takes a lot to just stay alive, process food, breath, move, and fight away bugs that go around whilst building immunity. A slower metabolism after age 60, he added, may mean that crucial organs are functioning less well as people age. It might be one reason that chronic diseases tend to occur most often in older people.Even college students might see the effects of the metabolic shift around age 20, Dr. Klein said.

“When they finish college they are burning fewer calories than when they started.”

And around age 60, no matter how young people look, they are changing in a fundamental way.


 



Now with that, we bring Exercise into the equation...

Biggest Loser weight loss .


Gretchen Reynolds who writes on wellness in the NYT reviewed a study of the biggest loser participants. One of the biggest lessons of the show appeared to be that extreme exercise, along with draconian calorie restriction, would lead to enormous weight loss. A new scientific analysis of the show and its aftermath, published last month in the journal Obesity, suggests many beliefs about “The Biggest Loser” may be misconceptions. The analysis tried to untangle what really happened to the contestants’ metabolisms and why some of them kept off weight better than others. It also looks into the complex role of exercise and whether staying physically active helped the contestants keep their weight under control for years, or not. A lower resting metabolic rate can mean we burn fewer calories over all. and our bodies are amazing at adapting to anything we teach it or prevail to it. Our bodies will learn how to become most efficient at any task we repeatedly do. It learns the most optimal way to work.


Starting more than a decade ago, Dr. Hall and his colleagues began the first of a series of experiments to find out. In a study from 2014, they compared 13 men and women who had lost massive amounts of weight by cutting calories, thanks to gastric bypass surgery, and 13 contestants from “The Biggest Loser,” whose extreme weight loss involved exercise as well as dieting. As expected, the bypass group shed muscle, as well as fat, while “The Biggest Loser” contestants kept most of their muscle and primarily dropped fat. But everyone’s resting metabolic rate dropped, and to about the same extent, whether they remained well-muscled or not.


for a 2016 study, they rechecked 14 of the same contestants six years after their competition, expecting their metabolisms to have rebounded by then. By this time, most of the contestants had regained weight. But their resting metabolisms remained stubbornly slow, burning an average of about 500 fewer daily calories than before they joined the show. The next year, a follow-up study concluded physical activity had helped some contestants stave off weight gain. If they moved around or formerly exercised for about 80 minutes most days, they added back fewer pounds than if they rarely worked out. But their exercise did not boost their resting metabolisms. The exercisers, in fact, showed the greatest relative declines in their resting metabolic rates. This is due to the fact that their bodies adapted to the repeated consistent cardio they were living by each day.


Perplexed, Dr. Hall recently began to reconsider the “Biggest Loser” studies in light of an emerging concept about how human metabolism fundamentally works. In the new analysis he looked at their resting metabolic rates. That number plummeted early in their “Biggest Loser” filming, he noted, when they slashed how much they ate, and their bodies, understandably, reduced the calories they burned to avoid starving. But in later years, when contestants typically returned to eating as they had before, their metabolisms stayed depressed because, he concluded — and this was key — most of them still exercised. The contestants were demonstrating the constrained energy model.



So, what could this rethinking of “The Biggest Loser” story mean for the rest of us, if we hope to keep our weight under control?


First and most fundamentally, it suggests that abrupt and colossal weight loss generally will backfire, since that strategy seems to send resting metabolic rates plunging more than would be expected, given people’s smaller body sizes. Don't focus on cutting out food and trying to get there on the fast track. this will lead to metabolic damage When people drop pounds gradually in weight-loss experiments, he pointed out, their metabolic changes tend to be less drastic.

Several studies show that low-calorie diets can decrease the number of calories the body burns by as much as 23%. this is known to be called Adaptive Thermogenesis (Müller, M. J., & Bosy-Westphal, A. (2013).


The relationship between metabolism and exercise and what type of activities are needed to prevent the constrained energy model from taking hold


This is also known as Energy Compensation with Exercise. In short, adaptation!

Attempts to sustain weight loss invoke adaptive responses involving the coordinate actions of metabolic, neuroendocrine, autonomic, and behavioral changes that “oppose” the maintenance of a reduced bodyweight (Rosenbaum, M., & Leibel, R. L. (2010).


Ok so DONT freak out. You doing your cardio a few times a week isnt going to stop your metabolism or hurt you. It will be great for reducing extra fat free mass which requires higher basel burn rate than fat. cardio is great for your heart health and fat burning. You need to think about it strategically.... if you were to do the same cardio Zone each day everyday, then your body will adjust and become more efficient, burning less. This is why adding in other activities such as skiing, rowing, swimming along with strength and resistance training and adequate recovery days will keep it Versitle.It is also critical that you change up your training on the bike. this is going through different periodizations to help improve your strength and fitness as well as target certain areas to adapt to and then move onto the next. Having a coach help guide you through will also aid in staying away from the prolonged adaptation as training will remain around adapting and then working on other areas to go along with it. a coach can help se when you are adapted and know what leves and extra stress to put on to keep you working upwards and not in a straight line.



 

if you are in a nutritional and training rut don't hesitate and check out options you can have for personalised coaching to reach your goals.




Sources


Citations:

Rosenbaum, M., & Leibel, R. L. (2010). Adaptive thermogenesis in humans. International journal of obesity (2005), 34 Suppl 1(0 1), S47–S55. https://doi.org/10.1038/ijo.2010.184


Müller, M. J., & Bosy-Westphal, A. (2013). Adaptive thermogenesis with weight loss in humans. Obesity (Silver Spring, Md.), 21(2), 218–228. https://doi.org/10.1002/oby.20027


Fothergill, E., Guo, J., Howard, L., Kerns, J. C., Knuth, N. D., Brychta, R., Chen, K. Y., Skarulis, M. C., Walter, M., Walter, P. J., & Hall, K. D. (2016). Persistent metabolic adaptation 6 years after "The Biggest Loser" competition. Obesity (Silver Spring, Md.), 24(8), 1612–1619. https://doi.org/10.1002/oby.21538

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